NOPF12-509
[DESCRIPTION]
[Title of Invention] LIGHT EXTRACTION TRANSPARENT
SUBSTRATE FOR ORGANIC EL ELEMENT, AND ORGANIC EL ELEMENT
USING THE SAME
5 [Technical Field]
The present invention relates to a light extraction
transparent substrate for an organic EL element, and an
organic EL element using the same.
[Background Art]
10 Organic electroluminescence elements (organic EL
elements) have been used as self-luminous elements for
image display devices such as displays, and for surface
light sources. Such an organic EL element (Organic Light
Emitting Diode: OLED) is generally fabricated by stacking
15 a transparent electrode serving as an anode, an organic
layer, and a metal electrode serving as a cathode in this
order on a transparent supporting substrate such as a glass
substrate or a transparent plastic film. Thus, upon
application of a voltage between the transparent electrode
20 and the metal electrode, electrons supplied from the
cathode and holes supplied from the anode are recombined
at the organic layer. Then, when excitons generated by
the recombination change from an excited state to a ground
state, EL emission occurs. Light of the EL emission goes
25 through the transparent electrode, and is extracted to the
outside on the transparent supporting substrate side.
1
NOPF12-509
However, such an organic EL element has a problem
that the light generated at the organic layer cannot be
extracted to the outside sufficiently. Specifically, the
problem is that a large proportion of the light generated
5 at the organic layer disappears as heat during repetition
of multiple reflections in the element, or propagates
inside the element and exits from end portions of the element,
so that a sufficient external extraction efficiency cannot
be achieved.
10 To solve the problem, for example, International
Publication No. WO2011/007878 (W02011/007878: PTL 1)
discloses an organic EL element comprising: a transparent
supporting substrate (A); a cured resin layer (B) staked
on the transparent supporting substrate; and a transparent
15 electrode (C) , an organic layer (D) , and a metal electrode
(E), which are stacked in this order on the cured resin
layer (B) , wherein the cured resin layer (B) has concavities
and convexities on a surface thereof, and a shape of the
concavities and convexities is such that when a
20 Fourier-transformed image is obtained by performing
two-dimensional fast Fourier transform processing on a
concavity and convexity analysis image obtained by
analyzing the shape of the concavities and convexities by
use of an atomic force microscope, the Fourier-transformed
25 image shows a circular or annular pattern substantially
centered at an origin at which an absolute value of
2
NOPF12-509
wavenumber is 0 urn l , and the circular or annular pattern
is present within a region where an absolute value of
wavenumber iswithinarangeof 10ym_1or less. Inaddition,
Hideo Takezoe et al. , "Enhanced Light Extraction Efficiency
5 of Organic Light Emitting Diode using Microlens based on
Buckling Phenomenon" described on p.12-34 5 of "Proceedings
(NPL 1) " of The 57th Meeting of The Japan Society of Applied
Physics and Related Societies issued in 2010 discloses that
an ultraviolet-cured resin having a concavity and convexity
10 shape is formed by a nanoimprinting method using a
polydimethylsiloxane (PDMS) in which a concavity and
convexity shape is formed by a buckling phenomenon, and
this ultraviolet-cured resin is used as a microlens for
an organic EL element.
15 The organic EL element described in PTL 1 and the
organic EL element using the microlens described in NPL
1 have sufficiently high light extraction efficiencies.
However, there is a demand for development of an organic
EL element whose angle-dependence of luminance and change
20 in chromaticity are sufficiently reduced at higher levels.
[Citation List]
[Patent Literature]
[PTL 1] International Publication No. W02011/007878
[Non Patent Literature]
25 [NPL 1] Hideo Takezoe et al. , "Enhanced Light Extraction
Efficiency of Organic Light Emitting Diode using Microlens
3
NOPF12-509
based on Buckling Phenomenon," "Proceedings (NPL 1)" of
The 57th Meeting of The Japan Society of Applied Physics
and Related Societies, issued in 2010, p.12-345.
[Summary of Invention]
5 [Technical Problem]
The present invention has been made in view of the
problems of the above-described conventional techniques,
and an object of the present invention is to provide a light
extraction transparent substrate for an organic EL element,
10 the light extraction transparent substrate being capable
of sufficiently improving the light extraction efficiency
of an organic EL element, sufficiently reducing the change
in chromaticity, and sufficiently reducing the
angle-dependence of luminance, and to provide an organic
15 EL element using the same.
[Solution to Problem]
The present inventors have conducted earnest study
to achieve the above-described object. As a result, the
present inventors have found that, surprisingly, the use
20 of the following transparent substrate as a transparent
substrate used by being disposed on an emitting surface
side of light in an organic EL element makes it possible
to sufficiently improve the light extraction efficiency
of the organic EL element, sufficiently reduce the change
25 in chromaticity, and sufficiently reduce the
angle-dependence of luminance, so that the above-described
4
NOPF12-509
object can be achieved. Here, the transparent substrate
comprises: a diffraction grating which comprises a first
concavity and convexity layer having first concavities and
convexities formed on a surface thereof and which is located
5 on a surface of the transparent supporting substrate, the
surface serving as an incident surface of the light of the
organic EL element when the transparent supporting
substrate is used in the organic EL element; and a microlens
which comprises a second concavity and convexity layer
10 having second concavities and convexities formed on a
surface thereof and which is located on a surface of the
transparent supporting substrate, the surface serving as
an emitting surface of the light of the organic EL element
when the transparent supporting substrate is used in the
15 organic EL element, wherein a shape of the first concavities
and convexities and a shape of the second concavities and
convexities are each such that when a Fourier-transformed
image is obtained by performing two-dimensional fast
Fourier transform processing on a concavity and convexity
20 analysis image obtained by analyzing the shape of the
concavities and convexities by use of an atomic force
microscope, the Fourier-transformed image shows a circular
or annular pattern substantially centered at an origin at
which an absolute value of wavenumber is 0 urn-1. This
25 finding has led to the completion of the present invention.
Specifically, a light extraction transparent
5
NOPF12-509
substrate for an organic EL element of the present invention
is a light extraction transparent substrate for an organic
EL element, which is used by being disposed on an emitting
surface side of light in the organic EL element, the light
5 extraction transparent substrate comprising:
a transparent supporting substrate;
a diffraction grating which comprises a first
concavity and convexity layer having first concavities and
convexities formed on a surface thereof and which is located
10 on a surface of the transparent supporting substrate, the
surface serving as an incident surface of the light of the
organic EL element when the transparent supporting
substrate is used in the organic EL element; and
a microlens which comprises a second concavity and
15 convexity layer having second concavities and convexities
formed on a surface thereof and which is located on a surface
of the transparent supporting substrate, the surface
serving as an emitting surface of the light of the organic
EL element when the transparent supporting substrate is
20 used in the organic EL element, wherein
a shape of the first concavities and convexities and
a shape of the second concavities and convexities are each
such that when a Fourier-transformed image is obtained by
performing two-dimensional fast Fourier transform
25 processing on a concavity and convexity analysis image
obtained by analyzing the shape of the concavities and
6
NOPF12-509
convexities by use of an atomic force microscope, the
Fourier-transformed image shows a circular or annular
pattern substantially centered at an origin at which an
absolute value of wavenumber is 0 urn-1.
5 In the light extraction transparent substrate for
an organic EL element of the present invention, the circular
or annular pattern of the Fourier-transformed image of the
shape of the first concavities and convexities is
preferably present within a region where an absolute value
10 of wavenumber is within a range of 10 urn"1 or less, and
the circular or annular pattern of the
Fourier-transformed image of the shape of the second
concavities and convexities is preferably present within
a region where an absolute value of wavenumber is within
15 a range of 1 urn"1 or less.
In the above-described light extraction transparent
substrate for an organic EL element of the present invention,
the first concavities and convexities preferably have an
average height of 30 to 100 nm and an average pitch of 10
20 to 700 nm, and the second concavities and convexities
preferably have an average height of 400 to 1000 nm and
an average pitch of 2 to 10 urn.
Moreover, in the above-described light extraction
transparent substrate for an organic EL element of the
25 present invention, an average value and a median of a depth
distribution of the first concavities and convexities
7
NOPF12-509
preferably satisfy a condition represented by the following
inequality (1):
0.95xY
The transparent supporting substrate 10 is not
particularly limited, and a known transparent substrate
5 usable for an organic EL element can be used as appropriate.
Examples of the transparent substrate include substrates
made of a transparent inorganic material such as glass;
substrates made of a resin such as polyethylene
terephthalate (PET), polyethylene terenaphthalate (PEN),
10 polycarbonate (PC), cycloolef in polymer (COP), polymethyl
methacrylate (PMMA), or polystyrene (PS); stacked
substrates having a gas barrier layer made of an inorganic
substance such as SiN, Si02, SiC, SiOxNy, Ti02, or Al203
formed on a surface of a substrate made of any of the
15 above-described resins; and stacked substrates having
substrates made of any of the above-described resins and
gas barrier layers made of any of the above-described
inorganic substances stacked alternately on each other.
In addition, the thickness of the transparent supporting
20 substrate 10 is preferably within a range from 1 to 500
urn.

The diffraction grating 11 is a layer (first concavity
and convexity layer) having first concavities and
25 convexities formed on a surface thereof. Examples of a
material (diffraction grating formation material) for
16
NOPF12-509
c
forming the diffraction grating (first concavity and
convexity layer ) 11 include resin materials (mater ials made
of curable resins) such as epoxy resin, acrylic resin,
urethaneresin, melamineresin, urearesin, polyester resin,
5 phenolic resin, and cross-linking type liquid crystal
resin; transparent inorganic layer formation materials
(for example, a sol containing a metal material such as
a metal alkoxide, in a case where a transparent inorganic
layer is formed by forming a concavity and convexity layer
10 by the sol-gel process) ; and the like. As described above,
the diffraction grating (concavity and convexity layer)
11 may be a cured resin layer obtained by curing the resin
material, or an inorganic layer formed by using the
transparent inorganic layer formation material. The
15 diffraction grating 11 is preferably an inorganic layer
from the viewpoint that a layer having higher
characteristics in heat resistance, mechanical strength,
and the like can be obtained. In addition, the thickness
of the first concavity and convexity layer is preferably
20 within a range from 0.01 to 500 um (more preferably 0.5
to 500 um). If the thickness of the first concavity and
convexity layer is less than the lower limit, heights of
the concavities and convexities formed on the surface of
the first concavity and convexity layer tend to be
25 insufficient. Meanwhile, if the thickness of the first
concavity and convexity layer exceeds the upper limit, an
17
NOPF12-509
effect of volume change of the diffraction grating
formation material (for example, a resin) which occurs upon
curing tends to be so large that the formation of the
concavity and convexity shape tends to be poor.
5 The diffraction grating 11 needs to be such that when
a Fourier-transformed image is obtained by performing
two-dimensional fast Fourier transform processing on a
concavity and convexity analysis image obtained by
analyzing the shape of the first concavities and
10 convexities formed on the surface of the first concavity
and convexity layer by use of an atomic force microscope,
the Fourier-transformed image shows a circular or annular
pattern substantially centered at an origin at which an
absolute value of wavenumber is 0 urn-1. By forming the shape
15 of the first concavities and convexities on the surface
of the concavity and convexity layer so that the
Fourier-transformed image can satisfy the above-described
requirement, a diffraction grating having a sufficiently
low wavelength dependence and a sufficiently low
20 directivity can be obtained.
In addition, the circular or annular pattern of the
Fourier-transformed image of the shape of the first
concavities and convexities is preferably present within
a region where an absolute value of wavenumber is within
25 a range of 10 urn-1 or less. By forming the shape of the
concavities and convexities on the surface of the concavity
18
NOPF12-509
and convexity layer so that the Fourier-transformed image
can satisfy the above-described requirement, it tends to
be possible to reduce the wavelength dependence and the
directivity of the diffraction grating at higher levels.
5 In addition, the pattern of the Fourier-transformed
image is more preferably annular, from the viewpoint that
more advanced effects on wavelength dependence and
directivity can be obtained. In addition, similarly from
the viewpoint that more advanced effects on wavelength
10 dependence and directivity can be obtained, the circular
or annular pattern of the Fourier-transformed image is more
preferably present within a region where an absolute value
of wave number is within a range from 1.25 to 10 urn"1 (further
preferably 1.25 to 5 urn"1) .
15 Note that "the circular or annular pattern of the
Fourier-transformed image" herein is a pattern observed
when bright spots in the Fourier-transformed image gather.
Hence, the term "circular" herein means that the pattern
of the gathering of the bright spots looks like a
20 substantially circular shape, and is a concept also
including a case where part of a contour looks like a convex
shape or a concave shape. Meanwhile, the term "annular"
means that the pattern of the gathering of the bright spots
looks like a substantially annular shape, and is a concept
25 also including a case where a shape of an outer circle or
an inner circle of the ring looks like a substantially
19
NOPF12-509
circular shape and further including a case where part of
the contours of the outer circle and/or the inner circle
of the ring looks like a convex shape or a concave shape.
Meanwhile, the phrase "the circular or annular
5 pattern is present within a region where an absolute value
of wavenumber is within a range of 10 urn"1 or less (preferably
1.25 to 10 urn"1, and further preferably 1.25 to 5 urn"1)"
herein means that 30% or more (more preferably 50% or more,
further more preferably 80% or more, and particularly
10 preferably 90% or more) of bright spots constituting the
Fourier-trans formed image are present within a region where
an absolute value of wavenumber is within a range of 10
urn"1 or less (preferably 1.25 to 10 urn"1, and further
preferably 1.25 to 5 urn-1) .
15 The Fourier-transformed image can be obtained by
analyzing the shape of the concavities and convexities
formed on the surface of the concavity and convexity layer
by use of an atomic force microscope, thereby obtaining
a concavity and convexity analysis image, and then
20 performing two-dimensional fast Fourier transform
processing on the concavity and convexity analysis image.
In addition, the concavity and convexity analysis
image can be obtained by analysis using an atomic force
microscope under the following analysis conditions:
25 Measurement mode: cantilever intermittent contact mode,
Material of cantilever: silicon,
20
NOPF12-509
mm
Lever width of cantilever: 40 urn,
Diameter of tip of cantilever chip: 10 nm.
As the atomic force microscope, commercially
available ones can be used as appropriate. For example,
5 a scanning probe microscope equipped with an environment
control unit "Nanonavi II Station/E-sweep" manufactured
by SII NanoTechnology Inc. can be used. In addition, it
is preferable to employ a cantilever intermittent contact
mode as the measurement mode of the atomic force microscope.
10 In this respect, when the scanning probe microscope
equipped with an environment control unit manufactured by
SII NanoTechnology Inc. is used, the dynamic force mode
(DMF mode) can be used. Moreover, as the cantilever, one
whose material is silicon, lever width is 4 0 urn, anddiameter
15 of a tip of a cantilever chip is 10 nm is preferably used,
and SI-DF40 can be used, for example. In addition, when
the analysis is conducted by use of an atomic force
microscope, it is preferable to observe the shape of the
concavities and convexities formed on the surface of the
20 concavity and convexity layer in the air at a temperature
of 25°C.
The two-dimensional fast Fourier transform
processing on the concavity and convexity analysis image
can be easily performed by electronic image processing
25 usinga computer equipped with software for two-dimensional
fast Fourier transform processing. In the two-dimensional
21
NOPF12-509
fast Fourier transform processing, a flattening process
including primary inclination correction is preferably
performed on the concavity and convexity analysis image.
Note that a concavity and convexity analysis image
5 displaying an area of 3 urn square (length: 3 urn, width:
3 jam) can be used as the concavity and convexity analysis
image on which the two-dimensional fast Fourier transform
processing is performed.
Inaddition, in the diffraction grating 11, an average
10 height of the first concavities and convexities formed on
the surface of the first concavity and convexity layer is
preferably 20 to 100 nm, more preferably 30 to 100 nm, and
further preferably 40 to 80 nm. If the average height of
the first concavities and convexities is less than the lower
15 limit, the height is so small relative to the wavelengths
of the visible light that necessary diffraction tends not
to occur. Meanwhile, suppose a case where the average
height exceeds the upper limit. In such a case, when the
obtained diffraction grating is used as an optical element
20 on the light extraction port side of an organic EL element,
not only destruction and life-shortening of the element
tend to occur because of heat generation which occurs when
the electric field distribution inside the EL layer becomes
nonuniform, and hence electric fields concentrate on a
25 certain position, but also replication of the concavities
and convexities by nanoimprinting tends to be difficult.
22
NOPF12-509
Note that the average height of the first concavities and
convexities refers to an average value of heights of the
concavities and convexities, where the heights of the
concavities and convexities (distances between concave
5 portions and convex portions in the depth direction) on
the surface of the first concavity and convexity layer are
measured. In addition, a value calculated as follows is
employed as the average value of the heights of the
concavities and convexities. Specifically, a concavity
10 and convexity analysis image is obtained by measuring the
shape of the concavities and convexities on the surface
in a randomly selected measuring region (preferably a
randomly selected measuring region of 3 urn square) by use
of a scanning probe microscope (for example, one
15 manufactured by SII NanoTechnology Inc. under the product
name of "E-sweep," or the like) Then, distances between
randomly selected concave portions and convex portions in
the depth direction are measured at 100 points or more in
the concavity and convexity analysis image, and the average
20 of the distances is determined.
An average pitch of the first concavities and
convexities formed on the surface of the first concavity
and convexity layer is preferably within a range from 10
to 700 nm, and more preferably within a range from 100 to
25 700 nm. If the average pitch of the first concavities and
convexities is less than the lower limit, the pitch is so
23
NOPF12-509
small relative to wavelengths of the visible light that
necessary diffraction tends not to occur. Meanwhile, if
the average pitch exceeds the upper limit, the diffraction
angle becomes so small that the functions as a diffraction
5 grating tend to be lost. Note that the average pitch of
the first concavities and convexities refers to an average
value of pitches of the first concavities and convexities,
where pitches of the first concavities and convexities on
the surface of the first concavity and convexity layer
10 (distances between adjacent convex portions or between
adjacent concave portions) are measured. In addition, a
value which can be calculated as follows is employed as
the average value of pitches of the first concavities and
convexities. Specifically, a concavity and convexity
15 analysis image is obtained by analyzing the concavities
and convexities on the surface by use of a scanning probe
microscope (for example, one manufactured by SII
NanoTechnology Inc. under the product name of "E-sweep,"
or the like) under the above-described analysis conditions .
20 Then, distances between randomly selected adjacent convex
portions or between randomly selected adjacent concave
portions are measured at 100 points or more in the concavity
and convexity analysis image, and the average of these
distances is determined. Moreover, the pitches of the
25 concavities and convexities can be easily achieved by use
of a master block according to the present invention to
24
NOPF12-509
c
be described later.
In addition, an average value and a median of a depth
distribution of the first concavities and convexities
formed on the surface of the diffraction grating 11
5 comprising the first concavity and convexity layer
preferably satisfy a condition represented by the following
inequality (1):
0.95xY (I I)
M =
X(N/2) +X( (N/2) + 1)
J
15 [in the formula (II), N represents the total number of
measuring points (the number of all the pixels), and M
represents the median of the depth distribution of the
concavities and convexities].
In addition, in the diffraction grating (first
20 concavity and convexity layer) 11, the average value (m)
28
NOPF12-509
of the depth distribution of the first concavities and
convexities in the inequality (1) is preferably 20 to 100
nm, and more preferably 40 to 80 nm. If the average value
(m) of the depth distribution is less than the lower limit,
5 the depths of the concavities and convexities are so small
that a sufficient diffraction effect cannot be obtained,
leading to a tendency that the light emission efficiency
is difficult to improve sufficiently. Meanwhile, if the
average value (m) exceeds the upper limit, the aspect ratio
10 of the concavities and convexities is too high. Hence,
in the use for an organic EL element, not only cracks are
easily formed in an electrode, but also a leakage current
is more easily generated during the use, so that a case
where the light emission efficiency decreases or a case
15 where light emission does not occur at all is caused, and
the life of the organic EL element tends to be shortened.
Moreover, in the diffraction grating ( first concavity
and convexity layer) 11, a kurtosis of the concavities and
convexities formed on the surface of the first concavity
20 and convexity layer is preferably -1.2 or more, more
preferably -1.2 to 1.2, further preferably -1.2 to 1, and
particularly preferably -1.1 to 0.0. If the kurtosis is
less than the lower limit, it tends to be difficult to
sufficiently suppress the generation of a leakage current
25 in the use for an organic EL element. Meanwhile, if the
kurtosis exceeds the upper limit, almost no concavities
29
NOPF12-509
and convexities exist in a sectional shape of the
diffraction grating (first concavity and convexity layer)
12, resulting in a state where projections or dents sparsely
exist. Hence, not only the light-extraction efficiency,
5 which is an advantage of the concavity and convexity
structure, cannot be improved sufficiently (the
diffraction effect cannot be obtained sufficiently), but
also the electric field is more likely to be concentrated
on the portions of the projections, so that leakage currents
10 tend to be generated.
As a method for measuring the kurtosis, the following
method is employed. Specifically, first, as in the case
of the above-described method for measuring the median (M)
of the depth distribution of the first concavities and
15 convexities and the average value (m) of the depth
distribution thereof, concavity and convexity depth data
are determined at 16384 (128 columns * 128 rows) or more
measuring points (65536 points in a case where a measuring
apparatus manufactured by SII NanoTechnology Inc. under
20 the product name of "E-sweep" is used, for example) in a
measuring region of 3 urn square. Then, the average value
(m) of the depth distribution of the concavities and
convexities and the standard deviation (o) of the depth
distribution of the concavities and convexities are
25 calculated on the basis of the concavity and convexity depth
data for the measuring points . Note that the average value
30
NOPF12-509
^5
(m) can be determined by calculation according to the
above-described formula (I) as described above. Meanwhile,
the standard deviation (o) of the depth distribution can
be determined by calculation according to the following
5 formula (III) :
[Math. 3]

The step (I) is a step of applying a block copolymer
solution comprising a block copolymer and a solvent onto
a surface of a base material, theblock copolymer comprising
5 first and second polymers (segments).
As the block copolymer, a copolymer having a first
polymer segment made of a first homopolymer and a second
polymer segment made of a second homopolymer which is
different from the first homopolymer is used. The second
10 homopolymer preferably has a solubility parameter which
is higher than a solubility parameter of the first
homopolymer by 0.1 to 10 (cal/cm3) 1/2 . If the difference
between the solubility parameters of the first and second
homopolymers is less than 0.1 (cal/cm3) 1/2, a regular micro
15 phase separation structure of the block copolymer is
difficult to form. Meanwhile, if the difference exceeds
10 (cal/cm3) 1/2, a uniform solution of the block copolymer
is difficult to prepare.
Examples of monomers serving as raw materials of
20 homopolymers usable as the first homopolymer or the second
homopolymer include styrene, methylstyrene, propylstyrene,
butylstyrene, hexylstyrene, octylstyrene, methoxystyrene,
ethylene, propylene, butene, hexene, acrylonitrile,
acrylamide, methyl methacrylate, ethyl methacrylate,
25 propyl methacrylate, butyl methacrylate, hexyl
methacrylate, octyl methacrylate, methyl acrylate, ethyl
37
NOPF12-509
acrylate, propylacrylate, butylacrylate, hexylacrylate,
octyl acrylate, methacrylic acid, acrylic acid,
hydroxyethyl methacrylate, hydroxyethyl acrylate,
ethylene oxide, propylene oxide, dimethylsiloxane, lactic
5 acid, vinylpyridine, hydroxystyrene, styrenesulfonate,
isoprene, butadiene, e-caprolactone, isopropylacrylamide,
vinyl chloride, ethylene terephthalate,
tetrafluoroethylene, and vinyl alcohol. Of these monomers,
styrene, methyl methacrylate, ethylene oxide, butadiene,
10 isoprene, vinylpyridine, and lactic acid are preferably
used from the viewpoints that the formation of phase
separation easily occurs, and that the concavities and
convexities are easily formed by etching.
In addition, examples of the combination of the first
15 homopolymer and the second homopolymer include combination
of two selected from the group consisting of a styrene-based
polymer (more preferably polystyrene), a poly(alkyl
methacrylate) (more preferably polymethyl methacrylate) ,
polyethylene oxide, polybutadiene, polyisoprene,
20 polyvinylpyridine, and polylactic acid. Of these
combinations, combinations of a styrene-based polymer and
a poly(alkyl methacrylate), combinations of a
styrene-based polymer and polyethylene oxide,
combinations of a styrene-based polymer and polyisoprene,
25 and combinations of a styrene-based polymer and
polybutadiene are more preferable, and combinations of a
38
NOPF12-509
t
styrene-based polymer and polymethyl methacrylate,
combinations of a styrene-based polymer and polyisoprene,
and combinations of a styrene-based polymer and
polybutadiene are particularly preferable, from the
5 viewpoint that the depths of the concavities and
convexities formed on the block copolymer can be further
increased by preferentially removing one of the
homopolymers by an etching treatment. A combination of
polystyrene (PS) andpolymethyl methacrylate (PMMA) ismore
10 preferable.
The number average molecular weight (Mn) of the block
copolymer is preferably 500000 or more, more preferably
1000000 or more, and particularly preferably 1000000 to
5000000. If the number average molecular weight is less
15 than 500000, the average pitch of the concavities and
convexities formed by the micro phase separation structure
of the block copolymer is so small that the average pitch
of the concavities and convexities of the obtained
diffraction grating becomes insufficient. Particularly
20 when illumination light ranging over wavelengths of the
visible region has to be diffracted, the average pitch is
desirably 10 to 700 nm, and in this respect the number average
molecular weight (Mn) of the block copolymer is preferably
500000 or more. Meanwhile, if a block copolymer having
25 a number average molecular weight (Mn) of 500000 or more
is used, it tends to be difficult to obtain a desired
39
NOPF12-509
t
concavity and convexity pattern by electroforming, unless
a second heating step is conducted after the etching step.
The molecular weight distribution (Mw/Mn) of the
block copolymer is preferably 1.5 or less, and more
5 preferably 1.0 to 1.35. If the molecular weight
distribution exceeds 1.5, a regular micro phase separation
structure of the block copolymer is difficult to form. Note
that the number average molecular weight (Mn) and the weight
average molecular weight (Mw) of the block copolymer are
10 values measured by gel permeation chromatography (GPC) and
converted to molecular weights of standard polystyrene.
A volume ratio between the first polymer segment and
the second polymer segment (the first polymer segment:the
second polymer segment) in the block copolymer is
15 preferably 3:7 to 7:3, and more preferably 4:6 to 6:4, for
creating a lamellar structure by self-assembly. If the
volume ratio is out of the above-described range, it tends
to be difficult to form a concavity and convexity pattern
owing to a lamellar structure.
20 In addition, the block copolymer solution used in
the step (I) can be prepared by dissolving the block
copolymer in a solvent. Examples of the solvent include
aliphatic hydrocarbons such as hexane, heptane, octane,
decane, and cyclohexane; aromatic hydrocarbons such as
25 benzene, toluene, xylene, and mesitylene; ethers such as
diethyl ether, tetrahydrofuran, and dioxane; ketones such
40
NOPF12-509
i
as acetone, methyl ethyl ketone, isophorone, and
cyclohexanone; ether alcohols such as butoxyethyl ether,
hexyloxyethyl alcohol, methoxy-2-propanol, and
benzyloxyethanol; glycol ethers such as ethylene glycol
5 dimethyl ether, diethylene glycol dimethyl ether, triglyme,
propylene glycol monomethyl ether, and propylene glycol
monomethyl ether acetate; esters such as ethyl acetate,
ethyl lactate, and y-butyrolactone; phenols such as phenol
and chlorophenol; amides such as N , N-dimethylformamide,
10 N, N-dimethylacetamide, and N-methylpyrrolidone;
halogen-containing solvents such as chloroform, methylene
chloride, tetrachloroethane, monochlorobenzene, and
dichlorobenzene; hetero element-containing compounds such
as carbon disulfide; and mixture solvents thereof. A
15 percentage content of the block copolymer in the block
copolymer solution is preferably 0.1 to 15% by mass, and
more preferably 0.3 to 5% by mass, relative to 100% by mass
of the block copolymer solution.
In addition, the block copolymer solutionmay further
20 comprise a different homopolymer (a homopolymer other than
the first homopolymer and the second homopolymer in the
block copolymer contained in the solution: for example,
when the combination of the first homopolymer and the second
homopolymer in the block copolymer is a combination of
25 polystyrene and polymethyl methacrylate, the different
homopolymer may be any kind of homopolymer other than
41
NOPF12-509
polystyrene and polymethyl methacrylate), a surfactant,
an ionic compound, an anti-foaming agent, a leveling agent,
and the like.
By adding the different homopolymer to the block
5 copolymer solution, it is possible to change the shape (for
example, the depths of the concavities and convexities,
and the like) of the micro phase separation structure formed
by the block copolymer. For example, a polyalkylene oxide
can be used to increase the depths of the concavities and
10 convexities formed by the micro phase separation structure.
As the polyalkylene oxide, polyethylene oxide or
polypropylene oxide is more preferable, and polyethylene
oxide is particularly preferable. In addition, as the
polyethylene oxide, one represented by the following
15 formula is preferable:
HO-(CH2-CH2-0)n-H
[in the formula, n represents an integer of 10 to 5000 (more
preferably an integer of 50 to 1000, and further preferably
an integer of 50 to 500)].
20 If the value of n is less than the lower limit, the
molecular weight is so low that the above-described effect
achieved by the different homopolymer contained tends to
be poor, because such a polyethylene oxide is lost due to
volatilization, vaporization, or the like during a heat
25 treatment at a high temperature. Meanwhile, if the value
of n exceeds the upper limit, the molecular weight is so
42
NOPF12-509
w
high that the molecular mobility is low. Hence, the speed
of the phase separation is lowered so that the formation
of the micro phase separation structure tends to be
inefficient.
5 In addition, the number average molecular weight (Mn)
of the different homopolymer is preferably 460 to 220000,
and more preferably 2200 to 46000. If the number average
molecular weight is less than the lower limit, the molecular
weight is so low that the above-described effect achieved
10 by the different homopolymer contained tends to be poor,
because the different homopolymer is lost due to
volatilization, vaporization, or the like during a heat
treatment at a high temperature. Meanwhile, if the number
average molecular weight (Mn) exceeds the upper limit, the
15 molecular weight is so high that the molecular mobility
is low. Hence, the speed of the phase separation is lowered,
so that the formation of the micro phase separation
structure tends to be inefficient.
The molecular weight distribution (Mw/Mn) of the
20 different homopolymer is preferably 1.5 or less, and more
preferably 1.0 to 1.3. If the molecular weight
distribution exceeds the upper limit, it tends to be
difficult to maintain the uniformity of the shape of the
micro phase separation. Note that the number average
25 molecular weight (Mn) and the weight average molecular
weight (Mw) are values measured by gel permeation
43
NOPF12-509
chromatography (GPC) and converted to molecular weights
of standard polystyrene.
In addition, when the different homopolymer is used,
it is preferable that the combination of the first
5 homopolymer and the second homopolymer in the block
copolymer be a combination of polystyrene and polymethyl
methacrylate (polystyrene-polymethyl methacrylate), and
the different homopolymer be a polyalkylene oxide. The
use of a polystyrene-polymethyl methacrylate block
10 copolymer and a polyalkylene oxide in combination as
described above further improves the orientation in the
vertical direction, making it possible to further increase
the depths of the concavities and convexities on the surface,
and also shorten the heat treatment time in the
15 manufacturing.
When the different homopolymer is used in the block
copolymer solution, the content thereof is preferably 100
parts by mass or less, and more preferably 5 parts by mass
to 100 parts by mass, relative to 100 parts by mass of the
20 block copolymer. If the content of the different
homopolymer is less than the lower limit, the effect
obtained by the different homopolymer contained tends to
be poor.
In addition, when the surfactant is used, the content
25 thereof is preferably 10 parts by mass or less relative
to 100 parts by mass of the block copolymer. Moreover,
44
NOPF12-509
when the ionic compound is used, the content thereof is
preferably 10 parts by mass or less relative to 100 parts
by mass of the block copolymer.
In addition, when the block copolymer solution
5 comprises the different homopolymer, the total percentage
content of the block copolymer and the different
homopolymer is preferably 0.1 to 15% by mass, and more
preferably 0 . 3 to 5% by mass , in the block copolymer solution
If the total percentage content is less than the lower limit,
10 it is difficult to uniformly apply the solution in a film
thickness sufficient to obtain a necessary film thickness.
If the total percentage content exceeds the upper limit,
it is relatively difficult to prepare a solution with
uniform dissolution in a solvent.
15 In addition, the base material used in the step (I)
is not particularly limited, and examples thereof include
substrates of resins such as polyimide, polyphenylene
sulfide (PPS), polyphenylene oxide, polyether ketone,
polyethylene naphthalate, polyethylene terephthalate,
20 polyarylate, triacetyl cellulose, and polycycloolefin;
inorganic substrates such as substrates of glass,
octadecyldimethylchlorosilane (ODS)-treated glass,
octadecyltrichlorosilane (OTS)-treated glass, organo
silicate-treated glass, silicon, and the like; and
25 substrates of metals such as aluminum, iron, and copper.
In addition, the base material may be subjected to surface
45
NOPF12-509
treatments such as an orientation treatment. Note that,
by treating a surface of a substrate of glass or the like
withODS, an organo silicate, or the like as described above,
a micro phase separation structure such as a lamellar
5 structure, a cylindrical structure, or a spherical
structure becomes more likely to be arranged
perpendicularly to the surface in a heating step described
later. This is because, by reducing the difference in
interfacial energy between the block copolymer component
10 and the surface of the base material, the domains of the
blocks constituting the block copolymer become more likely
to be oriented perpendicularly.
A method for applying the block copolymer solution
onto the base material is not particularly limited, and,
15 for example, a spin coating method, a spray coating method,
a dip coating method, a dropping method, a gravure printing
method, a screen print ing method, a relief print ing method,
a die coating method, a curtain coat ing method, oraninkjet
method can be employed as the method.
20 The thickness of the coating film of the block
copolymer formed on the base material is preferably 10 to
3000 nm, and more preferably 50 to 500 nm, in terms of the
thickness of a coating film after drying.

25 The step (II) is a step of drying the coating film
on the base material. The step of drying the coating film
46
NOPF12-509
is not particularly limited, and may be conducted in an
air atmosphere. In addition, the drying temperature in
this step is not particularly limited, as long as the solvent
can be removed from the coating film at the temperature.
5 The drying temperature is preferably 30 to 200°C, and more
preferably 40 to 100°C. Notethat, in some cases, the block
copolymer starts to form the micro phase separation
structure during the drying, so that concavities and
convexities are formed on the surface of the coating film
10 (thin film).

The step (III) isastep ( firstheatingstep) ofheating
the coating film dried in the step (II) at a temperature
not lower than a glass transition temperature (Tg) of the
15 block copolymer.
By heating the coating film at a temperature not lower
than the glass transition temperature (Tg) of the block
copolymer in the coating film as described above,
self-assembly of the block copolymer in the coating film
20 is allowed to proceed, so that micro phase separation of
the block copolymer into portions of the first polymer
segment and the second polymer segment can be caused. This
makes it possible to efficiently form the micro phase
separation structure.
25 In the first heating step (III), the heating
temperature is set at a temperature not lower than the glass
47
NOPF12-509
transition temperature (Tg). If the heating temperature
is lower than the glass transition temperature (Tg) of the
block copolymer, the molecular mobility of the polymer is
low. Hence, the self-assembly of the block copolymer does
5 not proceed sufficient ly, so that the format ion of the micro
phase separation structure tends to be insufficient, or
a longer heating time tends to be required to sufficiently
form the micro phase separation structure. In addition,
the upper limit of the heating temperature is not
10 particularly limited, unless the block copolymer is
thermally decomposed at the temperature. A method for
carrying out the first heating step is not particularly
limited, and, for example, a method may be employed in which
an oven or the like is used, as appropriate, in an air
15 atmosphere. Note that the drying and heating steps (steps
(II) and (III) ) may be performed continuously by gradually
elevating the heating temperature. Note that when the
drying and heating steps are continuously carried out by
gradually elevating the heating temperature as described
20 above, thedryingstep (step (II)) isincludedintheheating
step (step (III) ) .

The step (IV) is a step (etching step) of removing
the second polymer (segment) by an etching treatment on
25 the coating film subjected to the step (III), to thereby
form a concavity and convexity structure on the base
48
NOPF12-509
material.
In the etching step (IV), one (the second polymer
segment) of the polymer segments constituting the block
copolymer is selectively removed by etching utilizing the
5 following fact. Specifically, since the first polymer
segment and the second polymer segment have different
molecular structures, the first polymer segment and the
second polymer segment have different etching rates (ease
of etching). Hence, one (the second polymer segment) of
10 the polymer segments can be selectively removed depending
on the kinds of the homopolymers of the first polymer segment
and the second polymer segment. By removing the second
polymer segment from the coating film in the etching step,
an excellent concavity and convexity structure originated
15 from the micro phase separation structure (the structure
formed in the step (III)) of the block copolymer can be
efficiently formed on the coating film.
As the etching treatment for selectively removing
one of the polymer segments as described above, for example,
20 an etching method using a reactive ion etching method, an
ozone oxidation method, a hydrolysis method, a metal ion
staining method, an ultraviolet-ray etching method, or the
like can be employed, as appropriate. In addition, as the
etching treatment, a method may be employed in which
25 covalent bonds of the block copolymer are cleaved by a
treatment with at least one selected from the group
49
NOPF12-509
consisting of acids, bases, and reducing agents, and then
the coating film in which the micro phase separation
structure is formed is washed with a solvent capable of
dissolving only the one polymer segment, or the like,
5 thereby removing only the one polymer segment, while
keeping the micro phase separation structure.

The step (V) is a step ( second heating step) of heating
the concavity and convexity structure formed in the step
10 (IV) at a temperature not lower than a glass transition
temperature (Tg) of the first polymer (segment). The
second heating step (v) is performed as a so-called
annealing treatment, and the heating makes smoother a line
connecting the lowermost portion of each of the concave
15 portions and the vertex of a corresponding one of the convex
portions forming the concavity and convexity structure,
and makes smaller the kurtosis of the concavity and
convexity shape.
The heating temperature in the second heating step
20 (V) is preferably not lower than the glass transition
temperature of the first polymer segment remaining after
the etching (not lower than the glass transition
temperature of the first homopolymer) , and more preferably
not lower than the glass transition temperature of the first
25 homopolymer but not higher than a temperature (Tg+70°C)
which is higher than the glass transition temperature of
50
NOPF12-509
the first homopolymer by 70°C. If the heating temperature
is lower than the glass transition temperature of the first
homopolymer, a desired concavity and convexity structure
tends not to be obtained after the electroforming step to
5 be described later, or a longer heating time tends to be
required for forming a desired concavity and convexity
structure. Meanwhile, if the heating temperature exceeds
the upper limit, the concavity and convexity shape tends
to collapse to a great extent, because the entire first
10 polymer segment is melt or decomposed. As a method for
actually carrying out the second heating step, for example,
the second heating step may be performed, for example, in
an air atmosphere byusing an oven or the like, as appropriate,
as in the case of the first heating step.
15 Note that the sectional structure of the concavity
and convexity structure subjected to the etching step (IV)
can be so complicated that side surfaces of grooves defined
by the concavity and convexity structure are rough, and
concavities and convexities (including overhangs) are
20 formed in a direction perpendicular to the thickness
direction. The higher the molecular weight of the block
copolymer is, the more likely to be formed the concavities
and convexities present on the side surfaces of the convex
portion are. On the other hand, the molecular weight of
25 the block copolymer has a close relationship with the micro
phase separation structure, and, in turn, the pitches of
51
NOPF12-509
the diffraction grating obtained therefrom. In this
respect, even when a block copolymer having a relatively
high molecular weight is used in order to more efficiently
achieve a distribution of pitches preferable for the first
5 concavities and convexities, it can be said that it is
preferable to perform the second heating step as described
above in order to more reliably obtain a concavity and
convexity structure having such a desired pitch
distribution by electroforming. In the second heating
10 step (V) , by heating the concavity and convexity structure
subjected to the etching step (IV) , an annealing treatment
is performed on the first polymer segment constituting the
side surfaces of the concavity and convexity shape, so that
the sectional shape defined by the first polymer segment
15 can be a relatively smooth inclined surface (the lines each
connecting the lowermost portion of a concave portion and
the vertex of a convex portion can be made smoother) . As
a result, a mountain-like shape tapered upward from the
base material (referred to as "mountain-shaped structure"
20 herein) is obtained. The concavities and convexities on
the side surfaces are annealed by the heating as described
above, and the overhang portions turn into smooth inclined
surfaces by the heating. Hence, the concavities and
convexities of the mountain-shaped structure obtained in
25 the second heating step (V) make it possible to more easily
peel a metal layer deposited on the first polymer segment,
52
NOPF12-509
4&
and efficiently transfer the concavity and convexity shape
to the metal layer.
Here, if the side surfaces of the groves defined by
the concavity and convexity structure subjected to the
5 etching step (IV) are rough, and concavities and
convexities (including overhangs) are formed in the
direction perpendicular to the thickness direction,
portions to which the seed layer for the electroforming
is not attached are likely to be formed, and hence it tends
10 to be difficult to uniformly deposit the metal layer by
the electroforming. For this reason, when a first polymer
segment layer having a concavity and convexity structure
with rough side surfaces is used as it is, the mechanical
strength of the obtained mold tends to be low, and
15 deformation of the mold and defects such as pattern defects
tend to occur. In addition, it tends to be difficult to
obtain an electroforming film having a uniform film
thickness in the case of a complicated sectional structure
of concavities and convexities with rough side surfaces,
20 because, in electroforming (electroplating), the
thickness of the plating varies among portions depending
on the shape of a workpiece, and a metal to be plated is
more likely to be attracted to convex portions and
projecting corners of the workpiece, but is less likely
25 to be attracted to concave portions and recessed portions.
Moreover, suppose a case where such a complicated sectional
53
NOPF12-509
4
structure can be transferred to a mold obtained by
electrof orming. Even in such a case, when transfer of the
concavity and convexity shape is attempted by pressing the
mold to a diffraction grating formation material (for
5 example, a curable resin), the diffraction grating
formation material (for example, a curable resin) enters
spaces in the complicated sectional structure of the mold.
Hence, the mold cannot be peeled from the concavity and
convexity layer after curing, or portions of the mold with
10 low st rength may fracture , so that pattern defect s may occur .
In view of these points in combination, it is preferable
to perform the second heating step as described above from
the viewpoint of more reliably obtaining a concavity and
convexity structure having such a desired pitch
15 distribution by electroforming.
The base material having the concavities and
convexities (the concavities and convexities of the
mountain-shaped structure) obtained by performing the
second heating step (V) as described above can be suitably
20 used as a master for transfer to a metal in a subsequent
step. In addition, the average pitch of the concavities
and convexities is preferably within a range from 10 to
700 nm, and more preferably within a range from 100 to 700
nm. If the average pitch of the concavities and convexities
25 is less than the lower limit, the pitch is so small relative
to wavelengths of the visible light that diffraction of
54
NOPF12-509
the visible light, which is necessary for a diffraction
grating obtained by using such a master block, is less likely
tooccur. Meanwhile, if the average pi tch exceeds the upper
limit, the diffraction angle of a diffraction grating
5 obtained by using such a master block is so small that the
functions as a diffraction grating cannot be exhibited
sufficiently. Note that the average pitch of the
concavities and convexities refers to an average value of
pitches of the concavities and convexities, where pitches
10 (distances between adjacent convex portions or between
adjacent concave portions) of the concavities and
convexities on the surface of the concavity and convexity
layer (the layer made of the first polymer segment) formed
on the base material are measured. In addition, a value
15 calculated as follows is employed as the average value of
pitches of the concavities and convexities. Specifically,
a concavity and convexity analysis image of the shape of
the concavities and convexities on the surface is obtained
by use of a scanning probe microscope (for example, one
20 manufactured by SII NanoTechnology Inc. under the product
name of "E-sweep," or the like). Then, distances between
randomly selected adjacent convex portions or between
randomly selected adjacent concave portions are measured
at 100 points or more in the concavity and convexity analysis
25 image, and the average of these distances are determined.
Meanwhile, the average height of the concavities and
55
NOPF12-509
4
convexities formed on the base material is preferably
within a range from 20 to 100 nm, more preferably within
a range from 30 to 100 nm, and further preferably within
a range from 40 to 80 nm. If the average height of the
5 concavities and convexities is less than the lower limit,
the height is so insufficient relative to the wavelengths
of the visible light that the diffraction tends to be
insufficient. Meanwhile, suppose a case where the average
height exceeds the upper limit. In such a case, when the
10 obtained diffraction grating is used as an optical element
on the light extraction port side of an organic EL element,
destruction of the element and life-shortening of the
element tend to occur because of heat generation which
occurs when the electric field distribution inside the EL
15 layer becomes nonuniform, and hence electric fields
concentrate on a certain position. Note that the average
height of the concavities and convexities herein refers
to an average value of heights of the concavities and
convexities, where the heights of concavities and
20 convexities ( distances between concave port ions and convex
portions in the depth direction) on the surface of the
concavity and convexity layer (the layer made of the first
polymer segment) formed on the base material are measured.
In addition, a value calculated as follows is employed as
25 the average value of the heights of the concavities and
convexities. Specifically, a concavity and convexity
56
NOPF12-509
4^
analysis image of the shape of the concavities and
convexities on the surface is obtained by use of a scanning
probe microscope (for example, one manufactured by SII
NanoTechnology Inc. under the product name of "E-sweep,"
5 or the like). Then, distances between randomly selected
concave portions and convex portions in the depth direction
are measured at 100 points or more in the concavity and
convexity analysis image, and the average of these
distances is determined.
10 Note that characteristics (the average height, the
average pitch, the average value (m) , and the like) of the
concavities and convexities of the base material having
the concavities and convexities (the concavities and
convexities of the mount a in-shaped structure) can be easily
15 adjusted to desired ones, by adjusting the kind of the block
copolymer, the heating temperature in the heat treatment,
and the like, or by other means.

The step (VI) is a step of forming a seed layer on
20 the concavity and convexity structure subjected to the step
(V) . The step (VII) is a step of stacking a metal layer
on the seed layer by elect roforming ( elect rolytic plat ing ) .
The step (VIII) is a step of peeling the base material having
the concavity and convexity structure from the metal layer
25 and the seed layer. These steps are described below with
reference to Figs. 2 to 5.
57
NOPF12-509
Fig. 2 is a cross-sectional view schematically
showing a transfer master 30 in which a layer 21 made of
the first polymer segment and having concavities and
convexities of a mountain-shaped structure is formed on
5 a base material 20. Fig. 3 is a cross-sectional view
schematically showing a state where a seed layer 2 2 is formed
on the concavities and convexities on the surface of the
layer 21 made of the first polymer segment in the transfer
master 30. Fig. 4 shows a state where a metal layer 23
10 is formed on the surface of the seed layer 22 by
electroforming (electrolytic plating). Fig. 5 is a
cross-sectional view schematically showing a state where
the metal layer 23 and the seed layer 22 are peeled from
the transfer master 30.
15 In the step (VI) , the seed layer 22 is formed on the
concavity and convexity structure of the base material (the
transfer master 30) , the concavity and convexity structure
being obtained after the step (V) is performed (see Figs.
2 and 3).
20 The seed layer 22 is to serve as a conductive layer
for a subsequent electroforming treatment. A method for
forming the seed layer 22 is not particularly limited, and
it is possible to employ, as appropriate, a known method
capable of forming a so-called conductive layer on the
25 concavity and convexity-shaped layer 21 formed on the
surface of the base material 20 into such a shape that the
58
NOPF12-509
shape of the concavities and convexities is maintained.
For example, the seed layer 22 can be formed by a method
such as electroless plating, sputtering, or vapor
deposition.
5 In addition, the thickness of the seed layer 22 is
preferably 10 nm or more, and more preferably 100 nm or
more, in order to make uniform the current density in the
subsequent electroforming step, and thereby make uniform
the thickness of the metal layer to be deposited in the
10 subsequent electroforming step. In addition, a material
of the seed layer is not particularly limited, and it is
possible to use, for example, nickel, copper, gold, silver,
platinum, titanium, cobalt, tin, zinc, chromium, a
gold-cobalt alloy, a gold-nickel alloy, a boron-nickel
15 alloy, solder, a copper-nickel-chromium alloy, a
tin-nickel alloy, a nickel-palladium alloy, a
nickel-cobalt-phosphorus alloy, an alloy thereof, or the
like .
After the seed layer 22 is formed on the surface (the
20 concavity and convexity-shaped surface) of the layer 21
made of the first polymer segment of the transfer master
30 as described above, a metal layer is stacked on the seed
layer by electroforming (electrolytic plating) (Step
(VII): see Fig. 4).
25 The thickness of the metal layer 23 is not particularly
limited, and, for example, the total thickness including
59
NOPF12-509
the thickness of the seed layer 22 may be 10 to 3000 urn.
Any one of the above-described metal species usable for
the seed layer 22 can be used as a material of the metal
layer 23 deposited by the electrof orming . As the material
5 of the metal layer 23, nickel is preferable from the
viewpoints of wear resistance, releasability, and the like
of the obtained mold. In this case, it is preferable to
use nickel also for the seed layer 22.
In addition, conditions of the electroforming for
10 forming the metal layer 23 are not particularly limited,
and conditions employed in a known electrolytic plating
method may be employed as appropriate. In addition, the
current density for the elect ro forming may be, for example ,
0.03 to 10 A/cm2, from the viewpoints that a uniform metal
15 layer is formed by preventing bridge, and that the
electroforming time is shortened.
Note that when the mold comprising the metal layer
23 and the seed layer 22 is used, the metal layer 23 is
subjected to treatments such as the pressing to the resin
20 layer, the peeling, and washing. Hence, the metal layer
23 preferably has a moderate hardness and a moderate
thickness from the viewpoint of ease of these treatments.
From such a viewpoint, a diamond-like carbon (DLC)
treatment or a Cr plating treatment may be performed on
25 the surfaceof themetalmoldinorder to improve the hardness
of the metal layer 23 formed by the electroforming.
60
NOPF12-509
Alternatively, the surface hardness of the metal layer 23
may be increased by further performing a heat treatment
on the metal layer 23.
After the metal layer 23 is formed as described above,
5 a metal portion 31 comprising the metal layer 23 and the
seed layer 22 is peeled from the base material (the transfer
master 30) having the concavity and convexity structure
as shown in Fig. 5 (step (VIII)).
A master block (mold) for forming a diffraction
10 grating can be obtained by peeling the thus obtained metal
portion 31 comprising the seed layer 22 and the metal layer
2 3 from the base material having the concavity and convexity
structure. In other words, a master block (mold) 31 for
forming a diffraction grating comprising the seed layer
15 22 and the metal layer 23 canbe obtainedas described above.
A method for peeling the master block (mold) 31 for
forming a diffraction grating is not particularly limited,
and a known method can be employed as appropriate. A
physically peeling method may be employed, or a method may
20 be employed in which the mold (metal portion) 31 is peeled
off by removing by dissolution of the first homopolymer
and the remaining block copolymer by use of an organic
solvent, such as toluene, tetrahydrofuran (THF), or
chloroform, capable of dissolving them. In addition, in
25 the thus obtained mold 31, the characteristics of the
concavities and convexities of the transfer master 30 are
61
NOPF12-509
transferred (inverted).
In addition, when the master block (mold) 31 for
forming a diffraction grating is peeled from the transfer
master 30 (the base material 10 on which the layer 21 having
5 the concavities and convexities of the mountain-shaped
structure is stacked), part of the polymer, for example,
the first polymer segment, may remain in a state of being
attached to the surf ace of the mold, in some cases, depending
of the method for the peeling treatment. In such a case,
10 the polymer attached to and remaining on the surface of
the mold is preferably removed by washing. As a method
for the washing, wet washing or dry washing can be employed.
In addition, examples of the method for the wet washing
include methods for removal by washing with an organic
15 solvent such as toluene or tetrahydrofuran, a surfactant,
or an alkali-based solution. Note that when an organic
solvent is used, ultrasonic cleaning may be performed. In
addition, the polymer attached to and remaining on the
surface of the mold may be removed by electrolytic cleaning.
20 Meanwhile, an example of the method for the dry washing
is a method for removal by ashing using ultraviolet rays
or plasma. The polymer attached to and remaining on the
surface of the mold may be removed by washing in which a
combination of such wet washing and dry washing is employed.
25 In addition, after such washing, the mold may be rinsed
with pure water or purified water, dried, and then sub j ected
62
NOPF12-509
41
to ozone irradiation.
Hereinabove, the method for manufacturing a master
block (mold) for forming a diffraction grating comprising
the steps (I) to (VIII) is described. However, the method
5 for manufacturing such a master block (mold) for forming
a diffraction grating having the concavities and
convexities formed therein is not particularly limited,
and a known method can be employed as appropriate. For
example, a resin layer having a concavity and convexity
10 structure originated from the micro phase separation
structure of the block copolymer obtained by caring out
the steps (I) to (IV) (preferably, caring out the step (V)
in combination) as it is may be used as a mold.
Alternatively, by using a resin layer having a concavity
15 and convexity structure originated from the micro phase
separation structure of the block copolymer obtained by
caring out the steps (I) to (IV) (preferably, caring out
the step (V) in combination), a transfer material (a
material other than the above-described seed layer and
20 metal layer) is attached onto the surface of the concavity
and convexity structure of the resin layer, and the transfer
material is cured, and then detached. Thus, a concavity
and convexity transfer member having concavities and
convexities formed on a surface thereof is obtained, and
25 this concavity and convexity transfer member may be used
as a master block (mold) for forming a diffraction grating.
63
NOPF12-509
The transfer material is not particularly limited, and,
for example, may be a resin composition of a silicone-based
polymer (silicone rubber) , a urethane rubber, a norbornene
resin, a polycarbonate, polyethylene terephthalate,
5 polystyrene, polymethyl methacrylate, acrylic resin, a
liquid crystal polymer, an epoxy resin, or the like. In
addition, a method for attached the transfer material is
not particularly limited, and, for example, a vacuum vapor
deposition method; or various coating methods such as a
10 spin coating method, a spray coating method, a dip coating
method, a dropping method, a gravure printing method, a
screen printing method, a relief printing method, a die
coating method, a curtain coating method, an inkj et method,
and a sputtering method can be employed. In addition,
15 although conditions for curing the transfer material vary
depending on the kind of the transfer material used, for
example, the curing temperature is preferably within a
range from room temperature to 250°C, and the curing time
is preferably within a range from 0.5 minutes to 3 hours.
20 In addition, a method may be employed in which the transfer
material is cured by irradiation with energy rays such as
ultraviolet rays or electron beams. In this case, the
amount of irradiation is preferably within a range from
20 mJ/cm2 to 10 J/cm2. A final mold (master block) may be
25 manufactured by repeating the step using the transfer
material, and thus repeating the inversion and transfer
64
NOPF12-509
of the concavities and convexities . Even when concavities
and convexities (including overhangs) are formed on side
surfaces of convex portions of a concavity and convexity
structure (the concavity and convexity structure of the
5 master) not subjected to the inversion and transfer of the
concavities and convexities, the sectional shape can be
smoothed every time the step is performed (the lines each
connecting the lowermost portion of a concave portion and
the vertex of a corresponding convex portion can be made
10 smoother) by repeating the inversion and transfer of the
concavities and convexities by use of such a transfer
material. For this reason, even when concavities and
convexities (including overhangs) are formed on side
surfaces of convex portions of the concavity and convexity
15 structure (the concavity and convexity structure of the
master) not subjected to the inversion and transfer of the
concavities and convexities, the shape of the concavities
and convexities can be made a desired shape (for example,
the mountain-like shape as described above) by repeating
20 the inversion and transfer of the concavities and
convexities by use of such a transfer material.
In addition, the concavity and convexity shape of
the finally obtained master block (mold) for forming a
diffraction grating preferably has characteristics
25 similar to those of the above-described first concavities
and convexities. The shape of the concavities and
65
NOPF12-509
convexities can be easily adjusted by changing, as
appropriate, the kind of the polymer used, the heating
conditions in the heating step, and the like.
Next, a step (a step of manufacturing a diffraction
5 grating) is described in which the obtained master block
(mold) 31 for forming a diffraction grating is used.
Specifically, inthisstep, a diffract ion grating format ion
material (for example, a curable resin) is applied onto
a transparent supporting substrate, and is cured with the
10 master block being pressed thereto . Then, the master block
is detached, so that a concavity and convexity layer having
concavities and convexities formed thereon is stacked on
the transparent supporting substrate.
Figs. 6 to 8 are schematic diagrams for describing
15 a preferred embodiment of a method for manufacturing a
diffraction grating. Here, Fig. 6 is a cross-sectional
view schematically showing a state where a diffraction
grating formation material 11' (for example, a resin
material or a transparent inorganic layer formation
20 material) is applied onto the transparent supporting
substrate 10. Fig. 7 is a cross-sectional view
schematically showing a state where the diffraction grating
formation material is cured with the master block 31 being
pressed thereto. Fig. 8 is a cross-sectional view
25 schematically showing a state where concavities and
convexities are formed on the surface of the diffraction
66
NOPF12-509
grating (first concavity and convexity layer) 11 by
detaching the master block 31.
In the step of manufacturing a diffraction grating,
first, the diffraction grating formation material 11' (for
5 example, a curable resin or the like ) is applied onto the
transparent supporting substrate 10 (see Fig. 6) . After
that, with the master block (mold) 31 for forming a
diffraction grating being pressed to a coating film of the
diffraction grating formation material 11', the
10 diffraction grating formation material is cured (see Fig.
7) .
The transparent supporting substrate 10 is the same
as the transparent supporting substrate 10 described above.
In addition, the diffraction grating formation material
15 11' is a material (a resin material or a transparent
inorganic layer formation material) described as a material
for forming the first concavity and convexity layer
(diffraction grating) 11.
When a transparent inorganic layer formation material
20 is used as the diffraction grating formation material 11'
(when an inorganic layer is used as the concavity and
convexity layer), a sol containing a metal material is
preferably used to more efficiently form a concavity and
convexity layer to which the pattern is transferred by
25 sol-gel process. The sol containing a metal material is
not particularly limited. For example, when an inorganic
67
NOPF12-509
10
15
20
25
concavity and convexity layer made of silica is formed,
the sol may be a sol containing a silica precursor (metal
alkoxide). In addition, examples of the silica precursor
include metal alkoxides including tetraalkoxide monomers
such as tetramethoxysilane (TMOS), tetraethoxysilane
(TEOS), tetra-i-propoxysilane, tetra-n-propoxysilane,
tetra-i-butoxysilane, tetra-n-butoxysilane,
tetra-sec-butoxysilane, and tetra-t-butoxysilane;
trialkoxide monomers such as methyltrimethoxysilane,
ethyltrimethoxysilane, propyltrimethoxysilane,
isopropyltrimethoxysilane, phenyltrimethoxysilane,
methyltriethoxysilane,
propyltriethoxysilane,
phenyltriethoxysilane,
ethyltripropoxysilane,
isopropyltripropoxysilane,
methyltriisopropoxysilane,
ethyltriethoxysilane,
isopropyltriethoxysilane,
methyltripropoxysilane,
propyltripropoxysilane,
phenyltripropoxysilane,
ethyltriisopropoxysilane,
propyltriisopropoxysilane,
isopropyltriisopropoxysilane, and
phenyltriisopropoxysilane; polymers obtained by
polymerizing a small amount of any of these monomers;
composite materials obtained by introducing a functional
group or a polymer into part of any of the above-described
materials; and the like. Note that the sol only needs to
be capable of forming an inorganic layer in a sol-gel process,
and the kind of the metal material is not particularly
68
NOPF12-509
C
limited. Examples of the metal material other than metal
alkoxides include metal acetylacetonates, metal
carboxylates, oxychlorides, chlorides, mixtures thereof,
and the like. Moreover, the metal species in the metal
5 material is not particularly limited, and a metal species
other than silicon (Si) can also be used as appropriate,
as long as the metal species is capable of forming an
inorganic layer in a sol-gel process. For example, Ti,
Sn, Al, Zn, Zr, In, or the like may be used, as appropriate.
10 In addition, one of the above-described metal materials
may be used alone, or a combination of two or more thereof
may be used as a mixture. In addition, as the sol, one
obtained by mixing, as appropriate, precursors of the
inorganic layer (a layer made of a simple substance of the
15 metal or an oxide of the metal) can also be used . Inaddition,
when a mixture of TEOS and MTES is used as the sol, the
blending ratio thereof is not particularly limited, and
may be 1:1.
Moreover, examples of the solvent of the sol include
20 alcohols such as methanol, ethanol, isopropyl alcohol (IPA),
andbutanol; aliphatic hydrocarbons such as hexane, heptane,
octane, decane, and cyclohexane; aromatic hydrocarbons
such as benzene, toluene, xylene, and mesitylene; ethers
such as diethyl ether, tetrahydrofuran, and dioxane;
25 ketones such as acetone, methyl ethyl ketone, isophorone,
andcyclohexanone; ether alcohols suchasbutoxyethylether,
69
NOPF12-509
v
hexyloxyethyl alcohol, methoxy-2-propanol, and
benzyloxyethanol; glycols such as ethylene glycol and
propylene glycol; glycol ethers such as ethylene glycol
dimethyl ether, diethylene glycol dimethyl ether, and
5 propylene glycol monomethyl ether acetate; esters such as
ethyl acetate, ethyl lactate, and y-butyrolactone; phenols
such as phenol and chlorophenol; amides such as
N,N-dimethylformamide, N, N-dimethylacetamide, and
N-methylpyrrolidone; halogen-containing solvents such as
10 chloroform, methylene chloride, tetrachloroethane,
monochlorobenzene, and dichlorobenzene; hetero
element-containing compounds such as carbon disulfide;
water; and mixture solvents thereof. In particular,
ethanol and isopropyl alcohol are preferable, andmixtures
15 of ethanol or isopropyl alcohol with water are also
preferable.
Moreover, examples of additives which can be added
to the sol include polyethylene glycol, polyethylene oxide,
hydroxypropyl cellulose, and polyvinyl alcohol for
20 adjusting the viscosity; alkanolamines such as
triethanolamine, [3—diketones such as acetylacetone,
(3-ketoesters , formamide, dimethylf ormamide, anddioxane,
which are solution stabilizers; and the like.
In addition, the coating thickness of the diffraction
25 grating formation material is preferably within a range
in which the thickness of the first concavity and convexity
70
NOPF12-509
layer (diffraction grating) 11 can be 0.01 to 500 urn (more
preferably 0.5 to 500 urn). If the coating thickness of
the diffraction grating formation material is less than
the lower limit, the heights of the concavities and
5 convexities formed on the surface of the first concavity
and convexity layer tend to be insufficient. Meanwhile,
if the coating thickness exceeds the upper limit, an effect
of volume change of the diffraction grating formation
material (for example, a resin) which occurs upon curing
10 tends to be so large that the formation of the concavity
and convexity shape tends to be poor.
In addition, examples of methods which can be employed
as a method for applying the diffraction grating formation
material 11' (including the sol) onto the transparent
15 supporting substrate 10 include various coating methods
such as a spin coating method, a spray coating method, a
dip coating method, a dropping method, a gravure printing
method, a screen printing method, a relief printing method,
a die coating method, a curtain coating method, an inkjet
20 method, and a sputtering method. Moreover, when the
diffraction grating formation material is a resin material
(for example, a curable resin), for example, the curing
temperature is preferably within a range from room
temperature to 250°C, and the curing time is preferably
25 within a range from 0.5 minutes to 3 hours, although
conditions for curing the resin material varies depending
71
NOPF12-509
on the kind of the resin used. Alternatively, a method
may be employed in which the resin material is cured by
irradiation with energy rays such as ultraviolet rays or
electron beams. In such a case, the amount of irradiation
5 is preferably within a range from 20 mJ/cm2 to 5 J/cm2.
In addition, when the diffraction grating formation
material is cured by using the sol (when an inorganic layer
is formed) , a cured layer (an inorganic layer) may be formed
from the sol by employing, as appropriate, known conditions
10 which can be employed in the so-called sol-gel process,
depending on the metal species and the kind of the metal
material used. For example, when an inorganic layer
(concavity and convexity layer) made of silica is formed
by using a sol containing a silica precursor, the inorganic
15 layer can be formed by performing hydrolysis and a
polycondensation reaction to synthesize amorphous silica.
The hydrolysis and the polycondensation reaction are not
particularly limited, as long as these are performed under
conditions where the amorphous silica can be synthesized.
20 It is preferable to add an acid such as hydrochloric acid
or an alkali such as ammonia to adjust the pH of the sol.
It is more preferable to adjust the pH to 4 or lower or
10 or higher. In addition, additional water may be added
for performing the hydrolysis. Note that when additional
25 water is added for performing the hydrolysis as described
above, the amount of water added is preferably 1.5 times
72
NOPF12-509
t
or mo re in terms of molar ratio relative to the me talalkoxide
species. In addition, when a transparent inorganic layer
formation material is used as the diffraction grating
formation material 11' (when an inorganic layer is formed
5 as the concavity and convexity layer), it is preferable
to use a heated pressing roll for pressing the master block
(mold) 31 for forming a diffraction grating to the coating
film of the sol. By pressing the mold to the coating film
with heating as described above, the coating film can be
10 cured with the mold being pressed thereto. Hence, the
formation of the concavity and convexity layer tends to
be more efficient. In addition, after the inorganic layer
is formed by curing the transparent inorganic layer
formation material described above, it is preferable to
15 further heat the inorganic layer at a temperature of 200
to 1200°C for 5 minutes to 6 hours, from the viewpoint of
increasing the mechanical strength.
Note that the heat resistance of the diffraction
grating 11 tends to be improved in a case where the
20 diffraction grating 11 is formed of the transparent
inorganic layer formation material, as compared with a case
where a resin material is used. For this reason, when the
diffraction grating 11 formed of the transparent inorganic
layer formation material is used for manufacturing an
25 organic EL element, not only an organic EL element having
a higher power efficiency can be obtained because a film
73
NOPF12-509
of a low-resistant transparent electrode (forexample, ITO)
can be formed efficiently by the so-called sputtering with
heating, but also degradation due to high temperature can
be suppressed further sufficiently because the diffraction
5 grating 11 does not undergoes color change or the like even
when the organic EL element is used under a high-temperature
condition. In addition, when the diffraction grating 11
is formed of the transparent inorganic layer formation
material, it is also possible to wash the concavity and
10 convexity pattern surface of the diffraction grating 11
with a brush before the element is assembled. Here, a
comparison is made between a case where the transparent
inorganic layer formation material is used as a material
for forming the concavity and convexity layer and a case
15 where a resin material is used. In the former case, the
mechanical strength of the surface of the concavity and
convexity layer is higher, and the formation of scars on
the surface of the layer can be suppressed more sufficiently
during the brush-washing process (basically, no scars are
20 formed). Hence , the surf ace of the concavity and convexity
layer can be washed efficiently, and foreign substances
and the like on the surface can be removed more efficiently.
For this reason, defects due to foreign substances on the
surface or the like can be sufficiently suppressed (the
25 defective rate can be lowered). Moreover, a layer having
a better chemical resistance can be formed, and hence the
74
NOPF12-509
4$
alkaline resistance of the layer can be improved to a higher
level in a case where the diffraction grating 11 is formed
of the transparent inorganic layer formation material than
in a case where a resin material is used. For this reason,
5 various washing solvents can be used in the step of washing
the surface. In other words, the washing liquid is not
particularly limited in the washing step conducted before
the element is assembled, and alkalis or various organic
solvents can be used as appropriate. Moreover, as
10 described above, a layer having a better chemical
resistance can be formed in a case where the diffraction
grating 11 is formed of the transparent inorganic layer
formation material than in a case where a resin material
is used. Hence, damage due to a resist or a developer of
15 ITO patterning tends to be more reduced in the former case.
In addition, a higher level of UV resistance can be imparted
to the diffraction grating 11 in a case where the diffraction
grating 11 is formed of the transparent inorganic layer
formation material than in a case where a resin material
20 is used. Hence, when the diffraction grating 11 is formed
of the transparent inorganic layer formation material,
organic contaminants can be efficiently removed by UV ozone
washing, so that the defective rate due to organic
contaminants can be reduced. Moreover, even when the
25 diffraction grating 11 is used outdoors, degradation due
to sunlight can be sufficiently suppressed, and a higher
75
NOPF12-509
weather resistance tends to be achieved.
In addition, in the step of manufacturing a
diffraction grating, next, the master block 31 is detached
from the cured diffraction grating (first concavity and
5 convexity layer) 11 (see Fig. 8) . A method for detaching
the master block 31 from the cured diffraction grating
(first concavity and convexity layer) 11 as described above
is not particularly limited, and a known method can be
employed, as appropriate. Thus, the first concavity and
10 convexity layer (diffraction grating) 11 having
concavities and convexities formed thereon can be stacked
on the transparent supporting substrate 10.
Note that when the concavity and convexity structure
of the master block (mold 31) is transferred to the
15 diffraction grating formation material (for example, a
curable resin) in caring out this step, a mold-release
treatment may be performed on the master block in order
to improve the mold releasability from the diffraction
grating formation material. The mold-release treatment
20 is not particularly limited, and a scheme of lowering the
surface energy is employed, in general. Examples of the
mold-release treatment include a method in which the
concavity and convexity surface of the mold 31 is coated
with a mold release agent such as a fluorine-containing
25 material or a silicone resin, or subjected to a treatment
with a fluorine-containing silane coupling agent, a method
76
NOPF12-509
in which a film of diamond-like carbon is formed on the
surface, and the like.
Thus, the transparent supporting base member 10
provided with the diffraction grating 11 having a desired
5 pattern can be obtained. Further, the step of
manufacturing a diffraction grating 11 may be again carried
out by using the thus obtained transparent supporting base
member 10 provided with the diffraction grating 11 as a
master block (mold) for forming a diffraction grating.
10 Specifically, a replica having an inverted pattern may be
manufactured by using the transparent supporting base
member 10 provided with the diffraction grating 11 as a
master block. In this case, the replica may be used as
the diffraction grating 11. In addition, the step of
15 inversion and transfer may be carried out repeatedly, and,
for example, the transfer step may be repeated again by
using the replica having an inverted pattern as a master
block to form a child replica. A diffraction grating 11
in which first concavities and convexities are formed may
20 be finally formed by repeating the inversion and the
transfer of the concavities and convexities as described
above. Note that when replicas are sequentially
replicated as described above, a film may be stacked by
a vapor phase method such as the vapor deposition method
25 or the sputtering method on the surface, on which the
concavity and convexity pattern is formed, of the
77
NOPF12-509
diffraction grating (first concavity and convexity layer)
used as the master block. When the film is stacked as
described above, and the transfer or the like is performed
by applying a resin onto a surface of the film or by other
5 means, the adhesion with the resin (forexample, aUVcurable
resin) can be lowered, and the master block can be easily
peeled off. In addition, the vapor-deposition film may
be, for example, made of a metal such as aluminum, gold,
silver, platinum, or nickel or ametal oxide such as aluminum
10 oxide. In addition, the thickness of the film is preferably
5 to 500 nm. If the thickness is less than the lower limit,
a uniform film is difficult to obtain, and the sufficient
adhesion-lowering effect is not obtained. If the
thickness exceeds the upper limit, the shape of the master
15 block tends to be dull. When the concavity and convexity
layer of the replica is made of an UV curable resin, postcure
may be conducted as appropriate by irradiation again with
ultraviolet light or the like after the resin is cured.

20 The microlens 12 comprises a concavity and convexity
layer (second concavity and convexity layer) having second
concavities and convexities formed on a surface thereof.
As a material (microlens formation material) for forming
the microlens (second concavity and convexity layer) 12,
25 the same material (for example, a curable resin or a
transparent inorganic layer formation material) as that
78
NOPF12-509
used for manufacturing the diffraction grating 11 can be
used as appropriate. In this way, the microlens 12
(concavity and convexity layer) may be a cured resin layer
obtained by curing the resin material, or an inorganic layer
5 formed by using a transparent inorganic layer formation
material.
The thickness of the microlens (second concavity and
convexity layer) 12 is preferably within a range from 1
to 500 urn. If the thickness of the concavity and convexity
10 layer forming the microlens 12 is less than the lower limit,
heights of the concavities and convexities formed on the
surface of the concavity and convexity layer tend to be
insufficient. Meanwhile, if the thickness of the
concavity and convexity layer exceeds the upper limit, an
15 effect of volume change of the microlens formation material
(for example, a resin) which occurs upon curing tends to
be so large that the formation of the concavity and convexity
shape tends to be poor.
In addition, the microlens (second concavity and
20 convexity layer) 12 needs to be such that when a
Fourier-transformed image is obtained by performing
two-dimensional fast Fourier transform processing on a
concavity and convexity analysis image obtained by
analyzing the second concavity and convexity shape formed
25 on the surface by use of an atomic force microscope, the
Fourier-transformed image shows a circular or annular
79
NOPF12-509
pattern substantially centered at an origin at which an
absolute value of wave number is 0 urn"1. By forming the shape
of the concavities and convexities on the surface of the
concavity and convexity layer so that the
5 Fourier-transformed image can satisfy the above-described
condition, the concavity and convexity shape becomes
isotropic in any cross-sectional direction. Under such
a situation, when light incident on one surface (the surface
in contact with the substrate) side exits from the surface
10 on which the shape is formed, it is possible to sufficiently
reduce the angle-dependence of the emitted light and the
change in chromaticity.
In addition, the circular or annular pattern of the
Fourier-transformed image of the second concavity and
15 convexity shape is preferably present within a region where
an absolute value of wavenumber is within a range of 1 urn"1
or less. By forming the shape of the concavities and
convexities on the surface of the concavity and convexity
layer so that the Fourier-transformed image can satisfy
20 the above-described condition, the angle-dependence of the
emitted light and the change in chromaticity can be
sufficiently reduced at higher levels.
In addition, regarding the second concavity and
convexity shape, the circular or annular pattern is
25 preferably present within a region where an absolute value
of wavenumber is within a range from 0.05 to 1 urn-1, and
80
NOPF12-509
is more preferably present within a region where an absolute
value of wavenumber is within a range from 0.1 to 0.5 urn-1,
from the viewpoint of efficiently refracting or diffracting
an emission spectrum in the visible region (380 nm to 780
5 nm). If the circular or annular pattern is not present
within the region where the absolute value of wavenumber
is within the range, that is, if the number of bright spots
which form the circular or annular pattern in the
Fourier-transformed image and which are present within the
10 range is less than 30% of all bright spots, refraction
effective for a lens tends not to be obtained. In addition,
the pattern of the Fourier-transformed image of the second
concavities and convexities is more preferably annular from
the viewpoint that a sufficient effect is obtained on light
15 having wavelengths in the visible region (380 nm to 780
nm) . Note that the same method as that for obtaining the
Fourier-transformed image of the shape of the first
concavities and convexities can be employed as a method
for obtaining this Fourier-transformed image.
20 In addition, an average pitch of the second
concavities and convexities formed on the surface of the
microlens (second concavity and convexity layer) 12 is
preferably within a range from 2 to 1 0 um, and more preferably
within a range from 2.5 to 5 um. If the average pitch of
25 the concavities and convexities is less than the lower limit,
not only the light extraction effect tends to deteriorate
81
NOPF12-509
because a diffraction effect as a diffraction grating
becomes stronger than a refraction effect as a lens, but
also sufficient light emission tends not to be obtained
at some measurement positions because the angle-dependence
5 of the emitted light is increased. Meanwhile, if the
average pitch exceeds the upper limit, a diffraction effect
as a diffraction grating tends to be difficult to obtain,
so that the characteristics are at the same levels as those
of ordinary hemispherical lenses. Note that when a
10 microlens has an average pitch within the above-described
range in the micrometer size, a light incident angle can
be made closer to the right angle in the microlens. Hence,
a higher level of light extraction effect (lens effect)
can be obtained, and the microlens has a more improved
15 friction resistance than a microlens having a smaller-sized
average pitch.
The average pitch of the second concavities and
convexities refers to an average value of pitches of the
second concavities and convexities, where pitches
20 (distances between adjacent convex portions or between
adjacent concave portions) of the second concavities and
convexities on the surface of the second concavity and
convexity layer are measured. In addition, a value
calculated as follows is employed as the average value of
25 pitches of the second concavities and convexities.
Specifically, a concavity and convexity analysis image of
82
NOPF12-509
the shape of the concavities and convexities on the surface
is obtained by use of a scanning probe microscope (for
example, one manufactured by S 11 NanoTechnology Inc. under
the product name of "E-sweep, " or the like) . Then,
5 distances between randomly selected adjacent convex
portions or between randomly selected adjacent concave
portions are measured at 10 points or more in the concavity
and convexity analysis image, and the average of the
distances is determined.
10 In addition, an average height of the second
concavities and convexities formed on the surface of the
microlens (second concavity and convexity layer) 12 is
preferably within a range from 400 to 1000 nm, more
preferably within a range from 600 to 1000 nm, and further
15 preferably within a range from 7 00 to 900 nm. Iftheaverage
height (depth) of the concavities and convexities is less
than the lower limit, a refracting or diffracting effect
tends not to be obtained sufficiently. Meanwhile, if the
average height exceeds the upper limit, the mechanical
20 strength tends to be lwoered, so that cracks are more easily
formed during production or use. Note that the average
height of the concavities and convexities refers to an
average value of heights of concavities and convexities,
where heights of concavities and convexities (distances
25 between concave portions and convex portions in the depth
direction) on the surface of the concavity and convexity
83
NOPF12-509
layer are measured. In addition, a value calculated as
follows is employed as the average value of heights of the
concavities and convexities. Specifically, a concavity
and convexity analysis image of the shape of the concavities
5 and convexities on the surface is obtained by use of a
scanning probe microscope (for example, one manufactured
by SII NanoTechnology Inc. under the product name of
"E-sweep," or the like) . Then, distances between randomly
selected concave portions and convex portions in the depth
10 direction are measured at 10 points or more in the concavity
and convexity analysis image, and the average of these
distances is determined. Note that the concavity and
convexity shape having such a height (depth) can be formed
efficiently by utilizing a method for manufacturing a
15 microlens for an organic EL element of the present invention,
which is described later.
Moreover, when intensities of emission spectra are
measured for a randomly selected measuring point P on the
surface on which the concavities and convexities are formed,
20 where light L incident on the microlens on one surface side
on which the concavities and convexities are not formed
exits from the surface on which the concavities and
convexities are formed, the microlens (second concavity
and convexity layer) 12 preferably satisfies the condition
25 represented by the following inequality (2):
S(y(9)-y0(e))2<0.05 (2)
84
NOPF12-509
[in the formula, 9 represents 33 measuring angles ranging
from-8 0 ° to 80 ° with intervals of 5 degrees , y(6) represents
values obtained by normalizing values of intensities of
emission spectra measured at angles 9 with respect to a
5 value of an intensity of an emission spectrum measured at
an angle of 0°, and yo(9) represents values obtained by
normalizing theoretical values, determined from a
radiation pattern based on the Lambert law, of intensities
of emission spectra at the angles 9 with respect to a
10 theoretical value, determined from the radiation pattern,
of an intensity of an emission spectrum at an angle of 0°] .
Specifically, a value [ ( y ( 9)-yo(9 ) ) 2 ] obtained by squaring
a difference between a value (y(9)) obtained by normali zing
a value of an intensity of an emission spectrum measured
15 at an angle of 9 with respect to a value of an intensity
of an emission spectrum measured at an angle of 0° and a
value (yo(9)) obtained by normalizing a theoretical value
of an intensity of an emission spectra at the angle 9 based
on the Lambert law with respect to a theoretical value of
20 an intensity of an emission spectrum at an angle of 0° based
on the Lambert law is determined for each angle 9, and then
a total sum (2(y(9)-y0(9))2) of these values is found. In
this case, the total sum is preferably 0.05 or less. If
the value of the total sum of the squares of the differences
25 between the normalized values of the measured values and
the normalized values of the theoretical values is within
85
NOPF12-509
the above-described range, the second concavity and
convexity layer shows a radiation pattern similar to a
radiation pattern conforming to the Lambert law. Hence,
a second concavity and convexity layer having the value
5 of the total sum within the above-described range can be
used as a microlens 12 capable of more sufficiently lowing
the angle-dependence of the emitted light. Note that the
total sum (E(y(9)-y0(6))2) of the squares of the differences
between the normalized values of the measured values and
10 the normalized values of the theoretical values is more
preferably 0.03 or less, and particularly preferably 0.01
or less because the angle-dependence of the emitted light
and the change in chromaticity of the emitted light can
be reduced at higher levels.
15 Here, description will be given of a method for
determining the values (normalized values) obtained by
normalizing measured values of intensities of emission
spectra, and the like. For the measurement of such an
intensity of an emission spectrum, a known emission
20 spectrum measuring apparatus (for example, one
manufactured by Ocean Optics under the product name of
"USB-2000") capable of measuring an intensity of an
emission spectrum can be used as appropriate. In addition,
as a light source of the light to be incident on the concavity
25 and convexity layer for the purpose of measuring such an
intensity of an emission spectrum, an organic layer of an
86
NOPF12-509
M?
organic EL element may be used by stacking the light
extraction transparent substrate for an organic EL element
on an organic EL element. Alternatively, a lamp having
an emission spectrum in the visible region, such as a xenon
5 lamp, a halogen lamp, a metal halide lamp, a sodium lamp,
a mercury lamp, a fluorescence lamp, or an LED lamp, may
be used as the light source. Then, spectrum data of light
having wavelengths of 450 to 700 nm are measured at 33
measurement positions at which the measuring angles are
10 -80°, -75°, ..., -10°, -5°, 0°, 5°, 10°, ..., 75°, and 80°,
respectively, where a measuring angle in a case where a
measurement is conducted in a direction perpendicular to
the surface of the second concavity and convexity layer
12 is defined as 0°. Then, an actual measurement value
15 (measured value) of an intensity of an emission spectrum
is determined from an integral area of the spectrum data
at each angle. Thereafter, the actual measurement value
(measured value) of the intensity of the emission spectrum
at each angle 9 is divided by the actual measurement value
20 (measured value) of the intensity of the emission spectrum
at an angle of 0° for normalization. Thus, thevalue (y(9)),
which is a normalized measured value of the intensity of
the emission spectrum, can be obtained. Here, the
measuring angle 9 will be described in further detail with
25 reference to Fig . 9. A cent ral port ion of a light-receiving
surface for receiving an emission spectrum of an emission
87
NOPF12-509
spectrum measuring apparatus (light-receiving unit) is
termed as a light-receiving portion 0, and a randomly
selected measuring point on a surface S of the second
concavity and convexity layer is termed as P. In such a
5 case, the measuring angle 0 is an angle formed by a line
segmentPO (lineLl) connectingthe light-receiving portion
0 and the measuring point P with respect to a direction
which passes through the measuring point P and which is
perpendicular to the surface S of the second concavity and
10 convexity layer (a direction indicated by the dotted arrow
A in Fig. 2, hereinafter, this is simply referred to as
a "dotted line A" in some cases) . In addition, for the
measurement, the spectrum is measured with the distance
between the measuring point P and the light-receiving
15 portion 0 being set to 10 cm. While an angle formed by
the dotted line A and a line LI (line segment PO) is defined
as the measuring angle 9 as described above, spectrum data
of light having wavelengths of 450 to 700 nm are measured
at each of the 33 measurement positions. On the basis of
20 the obtained spectrum data, an actual measurement value
of an intensity of an emission spectrum (a value of integral
area of a graph of a spectrum of light having wavelengths
of 450 to 700 nm) is determined for each angle. Then, the
actual measurement value is divided by an actual
25 measurement value of an intensity of an emission spectrum
at an angle of 0° for normalization. Thus, the normalized
88
NOPF12-509
value (y(6) ) of the intensity of the emission spectrum can
be obtained for each angle 9. Note that, in the present
invention, a value (y(0)) obtained by normalizing the value
of the intensity of the emission spectrum measured at a
5 measuring angle of 0° is 1.0. Meanwhile, the radiation
pattern based on the Lambert law refers to a pattern of
an angular distribution (the so-called Lambert
distribution) of intensities (values of integral areas of
graphs of spectra of light having wavelengths of 450 to
10 700 nm) of emission spectra which can be obtained
theoretically from the Lambert law. Then, on the basis
of the theoretical angular distribution pattern (radiation
pattern) of intensities of the emission spectra obtained
based on the Lambert law, theoretical values of intensities
15 of emission spectra at the 33 measuring angles are
normalized with respect to a theoretical value of an
intensity of an emission spectrum at an angle of 0° . Thus,
a normalized value (yo(Q)) of the theoretical value of the
intensity of the emission spectrum at each angle 9 can be
20 determined. Note that, in the present invention, a
normalized value (yo(0)) of the theoretical value of the
intensity of the emission spectrum at an angle of 0° is
1.0.
In addition, suppose a case where the intensities
25 of emission spectra of light having wavelengths of 380 to
780 nm are measured for the microlens (second concavity
89
NOPF12-509
and convexity layer) 12 by employing the same method as
the above-described method for measuring the intensities
of the emission spectra and the like, and then a CIE u'v'
chromaticity diagram is obtained on the basis of the values
5 of the intensities of the emission spectra. In such a case,
the maximum value of the distance (Ac) between the color
coordinate at a measuring angle of 0° and the color
coordinate at each measuring angle is preferably 0.015 or
less, preferably 0.01 or less, and furtherpreferably 0.006
10 or less. If the maximum value of the color coordinate
distance exceeds the upper limit, the viewing angle
dependence of the color of the light emission tends to be
so great that a person can notice the color change when
seeing the light emission at various angles.
15 In addition, the microlens (second concavity and
convexity layer) 12 may be stacked on the transparent
supporting substrate 10 with a pressure-sensitive adhesive
layer and/or an adhesive layer interposed therebetween.
When the pressure-sensitive adhesive layer and/or the
20 adhesive layer is contained as described above, the
microlens (second concavity and convexity layer) 12 may
be stacked on the transparent resin substrate 10, for
example, by employing a method in which the microlens 12
is stacked on the transparent supporting substrate by using
25 an adhesive agent, a method in which the microlens 12 is
stacked on the transparent supporting substrate 10 by using
90
NOPF12-509
a pressure-sensitive adhesive agent, or the like.
Moreover, in this case, it is also possible to manufacture
the microlens (second concavity and convexity layer) 12
in the form of an independent film, and to laminate the
5 microlens ( second concavity and convexity layer ) 12 in this
form as it is on the surface of the transparent resin
substrate 10. In addition, in the case of such a lamination
type, the yield can be improved for the following reasons.
Specifically, when a scar or a defect is found in the
10 microlens (second concavity and convexity layer) 12, such
a portion can be removed. Moreover, when a defect is found
on the element side, the defective part can be removed.
As a material of the pressure-sensitive adhesive
layer and/or the adhesive layer, a known material (a
15 pressure-sensitive adhesive agent or an adhesive agent)
capable of adhering the microlens (second concavity and
convexity layer) 12 onto the transparent supporting
substrate 10 can be used as appropriate. For example, a
synthetic rubber-based pressure-sensitive adhesive agent
20 such as an acrylic pressure-sensitive adhesive agent, an
ethylene-vinyl acetate copolymer, a natural rubber-based
pressure-sensitive adhesive agent, polyisobutylene, butyl
rubber, a styrene-butylene-styrene copolymer, or a
styrene-inprene-styrene block copolymer; a
25 polyurethane-based pressure-sensitive adhesive agent, or
a polyester-based pressure-sensitive adhesive agent may
91
NOPF12-509
9
be used as appropriate, or a commercially available product
(an UV-curable optical adhesive agent NOA60, N0A61, N0A71,
NOA72, or N0A81 manufactured by Norland Products Inc. or
UV-3400 manufactured by TOAGOSEI CO., LTD.) may be used.
5 A method for applying the pressure-sensitive adhesive agent
or the adhesive agent is not particularly limited, and a
known method can be employed as appropriate. Note that
the pressure-sensitive adhesive agent or the adhesive agent
may be applied onto either the transparent supporting
10 substrate 10 or the microlens 12.
A protective layer is preferably stacked on the
surface of the microlens (second concavity and convexity
layer) 12 on which the concavity and convexity shape is
formed, from the viewpoint that the friction resistance
15 and the scratch resistance of the second concavities and
convexities on the surface are improved. As the protective
layer, a transparent film or a transparent inorganic vapor
deposition layer may be used as appropriate. The
transparent film is not particularly limited, and a known
20 transparent film can be used as appropriate. Examples
thereof include films made of transparent polymers such
as polyester-based resins inducing polyethylene
terephthalate; cellulose-based resins; acetate-based
resins; polyether sulfone-based resins;
25 polycarbonate-based resins; polyamide-based resins;
polyimide-based resins; polyolefin-based resins; and
92
NOPF12-509
acrylic resins. In addition, the transparent film may be
used as follows. Specifically, a pressure-sensitive
adhesive layer or an adhesive layer is formed on one surface
of the transparent film, and the transparent film is
5 laminated on the surface of the second concavity and
convexity layer on which the second concavities and
convexities are formed, with spaces being formed between
convex portions. As the pressure-sensitive adhesive agent
or the adhesive agent, for example, a synthetic
10 rubber-based pressure-sensitive adhesive agent such as an
acrylic pressure-sensitive adhesive agent, an
ethylene-vinyl acetate copolymer, a natural rubber-based
pressure-sensitive adhesive agent, polyisobutylene , butyl
rubber, a styrene-butylene-styrene copolymer, or a
15 styrene-inprene-styrene block copolymer; a
polyurethane-based pressure-sensitive adhesive agent; or
a polyester-based pressure-sensitive adhesive agent may
be used as appropriate.
In addition, when an inorganic vapor deposition layer
20 is stacked as the protective layer, a known metal material
capable of forming a transparent inorganic layer in the
vapor deposition method can be used as appropriate, and
example thereof include oxides, nitrides, sulfides, and
the like of metals such as Sn, In, Te, Ti, Fe, Co, Zn, Ge,
25 Pb, Cd, Bi, Se, Ga, and Rb. In addition, Ti02 can be
preferably used as the metal material, from the viewpoint
93
NOPF12-509
that deterioration due to oxidation can be prevented
sufficiently. Meanwhile, ZnS can be preferably used from
the viewpoint that high luminance can be obtained at low
costs. In addition, a method for forming the inorganic
5 vapor deposition layer is not particularly limited, and
the inorganic vapor deposition layer may be manufactured
as appropriate by using a known physical vapor deposition
apparatus.
Next, a method for manufacturing a microlens 12 is
10 described. As the method for manufacturing a microlens
12, a method (B) for manufacturing a microlens described
below can be preferably employed, for example. The method
(B) for manufacturing a microlens is a method comprising
a step of applying a microlens formation material (for
15 example, a resin material (a curable resin or the like)
or a transparent inorganic layer formation material) onto
one surface of a planate supporting material, curing the
microlens formation material with a master block for
forming a microlens being pressed thereto, and then
20 detaching the master block, thereby forming a second
concavity and convexity layer having concavities and
convexities formed on a surface thereof.
In the method (B) , a master block (mold) for forming
a microlens is used. The mold only needs to be capable
25 of forming the second concavity and convexity layer having
the second concavities and convexities formed thereon as
94
NOPF12-509
V
described for the microlens 12 in the following manner.
Specifically, a layer made of an uncured microlens
formation material is cured with the master block (mold)
for forming a microlens being pressed thereto, and thus
5 the shape of the concavities and convexities formed on the
mold is transferred (inverted) . Hence, as the mold, a mold
having a concavity and convexity shape on a surface thereof
is used, and the mold preferably has characteristics
(average height, average pitch, and the like) of the
10 concavity and convexity shape, which are the same as the
characteristics of the concavities and convexities formed
on the surface of the second concavity and convexity layer
forming the above-described microlens 12.
In addition, a method for manufacturing the master
15 block (mold) for forming a microlens is not particularly
limited. However, it is particularly preferable to employ
a method which comprises:
a step (i) of forming a vapor-deposition film under
a temperature condition of 70°C or above on a surface of
20 a polymer film made of a polymer whose volume changes by
heat, and then cooling the polymer film and the
vapor-deposition film, thereby forming concavities and
convexities of wrinkles on a surface of the
vapor-deposition film; and
25 a step (ii) of attaching a master block material onto
the vapor-deposition film, curing the master block material,
95
NOPF12-509
and then detaching the cured master block material from
the vapor-deposition film, thereby obtaining a master block
for forming a microlens.
Hereinafter, the steps (i) and (ii) for obtaining a master
5 block (mold) for forming a microlens are described with
reference to Figs. 10 to 13. Here, Fig. 10 is a
cross-sectional view schematically showing a state where
a polymer film 41 on which a vapor-deposition film is yet
to be formed is stacked on a substrate 40 for forming a
10 polymer film; Fig. 11 is a cross-sectional view
schematically showing a state where a vapor-deposition film
42 is formed on the polymer film 41, and concavities and
convexities of wrinkles are formed on a surface of the
vapor-deposition film 42 by cooling the polymer film 41
15 and the vapor-deposition film 4 2; Fig. 12 is a
cross-sectional view schematically showing a state where
a master block material 43' is attached onto the
vapor-deposition film 42 having the concavities and
convexities formed thereon; and Fig. 13 is a
20 cross-sectional view schematically showing a state where
a master block 43 obtained by curing the master block
material 43' is detached from the vapor-deposition film
42.

25 The step (i) is a step of forming a vapor-deposition
film under a temperature condition of 70°C or above on a
96
NOPF12-509
surface of a polymer film made of a polymer whose volume
changes by heat, and then cooling the polymer film and the
vapor-deposition film, thereby forming concavities and
convexities of wrinkles on a surface of the
5 vapor-deposition film. In this step, first, the polymer
film 41 made of a polymer whose volume changes by heat is
prepared on the substrate 40 for forming a polymer film.
As the polymer whose volume changes by heat, one whose volume
changes by heating or cooling (for example, one having a
10 coefficient of thermal expansion of 50 ppm/K or more) can
be used as appropriate. As the polymer, a silicone-based
polymer is more preferable, and a silicone-based polymer
containing polydimethylsiloxane is particularly
preferable, from the viewpoint that the concavities and
15 convexities of wrinkles are easily formed on the surface
of the vapor-deposition film 42, because the difference
between the coefficient of thermal expansion of the polymer
and the coefficient of thermal expansion of the
vapor-deposition film 42 is large, and because the polymer
20 has a high flexibility.
A method for forming the polymer film 41 is not
particularly limited, and, for example, a method can be
employed in which the polymer is applied onto the substrate
40 for forming a polymer film which is capable of supporting
25 the polymer film, by employing a spin coating method, a
dip coating method, a dropping method, a gravure printing
97
NOPF12-509
method, a screen printing method, a relief printing method,
a die coating method, a curtain coating method, an inkjet
method, a spray coating method, a sputtering method, a
vacuum vapor deposition method, or the like.
5 In addition, the substrate 40 for forming a polymer
film is not particularly limited, and a known substrate
(a glass substrate or the like) which can be used for forming
a polymer film can be used as appropriate. In addition,
the thickness of the thus formed polymer film 41 is
10 preferably within a range from 10 to 5000 urn, and more
preferably within a range from 10 to 2000 urn. Note that
although the polymer film 41 kept stacked on the substrate
40 is used in this embodiment, the polymer film 41 may be
used after detached from the substrate 40.
15 In addition, in the step (i) , after the polymer film
41 is prepared as described above, a vapor-deposition film
42 is formed on a surface of the polymer film 41 under a
temperature condition of 70°C or above. The temperature
at which the vapor-deposition film 42 is formed needs to
20 be 70°C or above, and is more preferably 90°C or above.
If the temperature is lower than 70°C, the concavities and
convexities of wrinkles cannot be formed sufficiently on
the surface of the vapor-deposition film. As the method
for forming the vapor-deposition film 42, a known method
25 such as a vapor deposition method or a sputtering method
can be employed as appropriate. Of these methods, a vapor
98
NOPF12-509
deposition method is preferably employed from the viewpoint
of maintaining the shape of the concavities and convexities
formed on the surface of the polymer film. In addition,
a material of the vapor-deposition film 42 is not
5 particularly limited, and examples thereof include metals
such as aluminum, gold, silver, platinum, and nickel; and
metal oxides such as aluminum oxide.
Moreover, in the step (i), after the vapor-deposit ion
film 42 is formed on the surface of the polymer film 41
10 as described above , concavities and convexities of wrinkles
are formed on the surface of the vapor-deposition film 42
by cooling the polymer film 41 and the vapor-deposition
film 42 (see Fig. 11). When the polymer film 41 and the
vapor-deposition film 42 are cooled after the
15 vapor-deposition film 42 is formed on the polymer film 41
as described above, the volume of each of the polymer film
41 and the vapor-deposition film 42 changes. However,
since there is a difference between the coefficient of
thermal expansion of the material forming the polymer film
20 41 and the coefficient of thermal expansion of the material
forming the vapor-deposition film 42, the layers have
different volume change ratios, and hence concavities and
convexities of wrinkles (the so-called bucking pattern or
the so-called Turing pattern) are formed on the surface
25 of the vapor-deposition film 42 as shown in Fig. 11. In
addition, the temperatures of the polymer film 41 and the
99
NOPF12-509
vapor-deposition film 42 after the cooling are preferably
40°C or below. If the temperatures of the polymer film
41 and the vapor-deposition film 4 2 after the cooling exceed
the upper limit, it tends to be difficult to form the
5 concavities and convexities of wrinkles on the surface of
the vapor-deposition film. Moreover, the rate of
temperature drop in cooling the polymer film 41 and the
vapor-deposition film 42 is preferably within a range from
1 to 80°C/minute. If the rate of temperature drop is less
10 than the lower limit, the concavities and convexities tends
to be relaxed. Meanwhile, if the rate of temperature drop
exceeds the upper limit, scars such as cracks tend to be
easily formed on the surfaces of the polymer film and the
vapor-deposition film.
15
The step (ii) is a step of attaching a master block
material onto the vapor-deposition film, curing the master
block material, and then detaching the cured master block
material from the vapor-deposition film, thereby obtaining
20 a master block for forming a microlens . Inthisstep, first,
a master block material 43' is attached onto the surface
of the vapor-deposition film 42 (the surface having the
concavity and convexity shape) (see Fig. 8) .
The master block material 43' is not particularly
25 limited, as long as the obtained master block is capable
of maintaining the strength, hardness, and the like enough
100
NOPF12-509
c
to be used as a mold for the concavity and convexity shape.
Examples of the master block material 43' include inorganic
substances such as nickel, silicon, silicon carbide,
tantalum, glassy carbon, silica glass, and silica; resin
5 compositions such as silicone-based polymers (silicone
rubbers), urethane rubbers, norbornene resins,
polycarbonates, polyethylene terephthalate, polystyrene,
polymethyl methacrylate, acrylic, and liquid crystal
polymers. Of these master block materials 43',
10 silicone-based polymers, nickel, silicon, silicon carbide,
tantalum, glassy carbon, silica glass, and silica are more
preferable, silicone-based polymers are further more
preferable, and silicone-based polymers containing
polydimethylsiloxane are particularly preferable, from
15 the viewpoints of moldability, followability to a fine
pattern, and mold releasability.
In addition, a method for attaching the master block
material 43' onto the surface of the vapor-deposition film
42 on which the concavity and convexity shape is formed
20 as described above is not particularly limited, and,
examples of employable methods include electroplating; a
vacuum vapor deposition method; and various coating methods
such as a spin coating method, a spray coating method, a
dip coating method, a dropping method, a gravure printing
25 method, a screen printing method, a relief printing method,
a die coating method, a curtain coating method, an inkjet
101
NOPF12-509
%
method, and a sputtering method.
In addition, in the step (ii) , after the master block
material 43' is attached onto the surface of the
vapor-deposition film 42 as described above, the master
5 block material43' is cured. General conditions for curing
the master block material 43' cannot be specified, because
the conditions vary depending on the kind of the master
block material used. However, for example, when a resin
material is used, it is preferable to set a curing
10 temperature within a range from room temperature to 250°C,
and a curing time within a range from 0. 5 minutes to 3 hours,
depending on the kind of the material. In addition, a
method may be employed in which the master block material
43' is cured by irradiation with energy rays such as
15 ultraviolet rays or electron beams, depending on the kind
of the master block material 43' . In such a case, the amount
of irradiation is preferably within a range from 20 mJ/cm2
to 10 J/cm2.
In addition, in the step (ii) , after the master block
20 material 43' on the surface of the vapor-deposition film
42 is cured as described above, a master block 43 for forming
a microlens is obtained by detaching a layer 43 obtained
by curing the master block material 43' from the
vapor-deposition film 42 as shown in Fig. 13. A method
25 for detaching the master block 4 3 from the vapor-deposition
film 42 as described above is not particularly limited,
102
NOPF12-509
and a known method can be employed as appropriate.
Moreover, from the viewpoint that the second
concavities and convexities can be formed more efficiently,
the following first to fifth steps may further be carried
5 out by using the master block 43 obtained by caring out
the steps (i) and (ii):
a first step of applying a curable resin onto one
surface of a supporting material, curing the curable resin
with the master block 43 being pressed thereto, and
10 detaching the master block 43, thereby obtaining a first
concavity and convexity resin film being located on the
supporting material and having concavities and convexities
formed thereon;
a second step of applying a polymer whose volume
15 changes by heat onto a surface of the first concavity and
convexity resin film, curing the polymer, and then
detaching the cured polymer film, thereby obtaining a
second polymer film having concavities and convexities
formed on a surface thereof;
20 a third step of forming a vapor-deposition film under
a temperature condition of 70°C or above on the surface
on which the concavities and convexities are formed, and
then cooling the polymer film and the vapor-deposition film
to form concavities and convexities of wrinkles on a surface
25 of the vapor-deposit ion film, thereby obtaining a laminate ;
a fourth step of applying a curable resin onto one
103
NOPF12-509
surface of another supporting material to obtain a coating
film, then curing the curable resin with the concavity and
convexity surface of the laminate being pressed to the
coating film, and detaching the laminate, thereby obtaining
5 a second concavity and convexity resin film being located
on the supporting material and having concavities and
convexities formed thereon; and
a fifth step of attaching a master block material
onto the second concavity and convexity resin film, curing
10 the master block material, and then detaching the cured
master block material from the vapor-deposition film,
thereby obtaining a master block. In addition, it is also
possible to repeat the first to fifth steps by using the
master block obtained in the fifth step. Alternatively,
15 after the first to fifth steps are cared out, it is also
possible to repeat only the third to fifth steps by using
the concavity and convexity surface of the master block
obtained in the fifth step as the surface on which the
concavities and convexities are formed described in the
20 thirdstep. In addition, the concavity and convexity resin
film obtained in the second step or the fourth step may
be used as a master block. When a master block in which
the shape of the concavities and convexities formed in the
master block 43 is sequentially replicated (inverted or
25 transferred) is manufactured by repeating the first to
fifth steps, by repeating part of the first to fifth steps
104
NOPF12-509
after the first to fifth steps are carried out, by caring
out part of the first to fifth steps, or by other means,
the wrinkles can be deepened every time the vapor deposition
step is repeated. Hence, the average height of the
5 concavities and convexities formed on the surface of the
master block can be increased. In addition, a microlens
having higher performances can be formed by using a master
block whose average height of the concavities and
convexities is increased as described above as a master
10 block for forming a microlens. Note that how many times
the steps for replicating the concavity and convexity shape
formed on the first master block (for example, the first
to fifth steps) are repeated, what steps are repeated, and
the like can be changed as appropriate depending on the
15 intended design (the pitches and the heights (depth) of
concavities and convexities) of the concavity and convexity
shape, the kind of material used, and the like. Thus, the
characteristics of the concavities and convexities can be
adjusted more easily, so that the same characteristics as
20 those of the above-described second concavities and
convexities can be achieved.
In addition, the same polymer as described in the
step (i) can be used as the polymer whose volume changes
by heat used in each of the first step and the second step.
25 In addition, as the curable resin used in the first step
and the second step, the same resin material ( curable resin)
105
NOPF12-509
as that used in the formation of the above-described first
concavity and convexity layer can be used as appropriate.
In addition, the supporting material is not particularly
limited, as long as the curable resin can be applied onto
5 the supporting material, and can be supported thereon. A
known base material can be used as appropriate, and examples
thereof include base materials including substrates of
resins such as polyimide, polyphenylene sulfide,
polyphenylene oxide, polyether ketone, polyethylene
10 naphthalate, polyethylene terephthalate, polyarylate,
triacetyl cellulose, and polycycloolefin; inorganic
substrates such as glass and silicon substrates; and
substrates of metals such as aluminum, iron, and copper;
andthelike. Moreover, the method for applying the curable
15 resin, the method for curing the curable resin, and the
like are not particularly limited, and the above-described
method for applying the resin material (curable resin) and
the above-described method for curing the resin material
(curable resin) can be employed as appropriate. Moreover,
20 the third step is the same as the step described in the
above-described concavity and convexity shape formation
step, except that the polymer film obtained in the second
step is used. In addition, as the curable resin used in
each of the fourth step and the fifth step, the same resin
25 material (curable resin) as that used for forming the
above-described first concavity and convexity layer can
106
NOPF12-509
be used as appropriate. Moreover, the same master block
material as that described in the step (ii) or the like
can be used as the master block material used in each of
the fourth step and the fifth step, and the same methods
5 as those described for the step (ii) and the like may be
employed as the method for applying the master block
material and the like.
In addition, when a polymer whose volume changes by
heat is used as the master block material in the method
10 for manufacturing a master block 43 for forming a microlens,
the steps (i) and (ii) may be repeated by using the obtained
master block as the polymer film. Also by such a method,
wrinkles formed on the surface of the master block can be
deepened, and the average height of the concavities and
15 convexities formed on the surface of the master block can
be increased.
Note that, in the method for manufacturing the master
block 43 for forming a microlens, a desired concavity and
convexity shape can be easily formed by changing, as
20 appropriate, the kind of the resin used, the steps to be
repeated, and the like depending on the intended design
of the concavity and convexity structure.
Hereinabove, the method for manufacturing a master
block (mold) for forming a microlens comprising the steps
25 (i) and (ii) is described. However, the method for
manufacturing a master block (mold) for forming a microlens
107
NOPF12-509
is not particularly limited, and a known method can be
employed as appropriate. For example, a master block
(mold) for forming a microlens, the master block having
desired concavities and convexities formed thereon, may
5 be manufactured by employing a method similar to the above
described method for manufacturing a master block (mold)
for forming a diffraction grating. Note that, likewise,
a method in which the steps (i) and (ii) are carried out
may be employed as the method for manufacturing a master
10 block (mold) for forming a diffraction grating.
Next, description is given of a step (microlens
formation step) in which the obtained mold for forming a
microlens is used. Specifically, in this step, amicrolens
formation material (for example, a resin material (a
15 curable resin) or a transparent inorganic layer formation
material) is applied onto one surface of a planate
supporting material, and is cured with a master block for
forming a microlens being pressed thereto. Then, the
master block is detached, so that a second concavity and
20 convexity layer having concavities and convexities formed
on a surface thereof is formed.
In the microlens formation step, first, a microlens
formation material (for example, a curable resin) is
applied onto one surface of the planate supporting material,
25 and is cured with the master block for forming a microlens
being pressed thereto. This step is basically the same
108
NOPF12-509
as the above-described step of manufacturing a diffraction
grating, except that the master block for forming a
microlens is used instead of the master block for forming
a diffraction grating.
5 As the microlens formation material, the same
material as the material for forming the first concavity
and convexity layer (diffraction grating formation
material) can be used as appropriate. In addition, the
planate supporting material is not particularly limited,
10 as long as the microlens formation material can be applied
onto the planate supporting material, and can be supported
thereon. A known base material (for example, a glass base
material, a resin film (a film of TAC, PET, COP, PC, or
the like), or the like) can be used as appropriate. In
15 addition, it is also possible to preferably use the
transparent supporting substrate 10 for an organic EL
element as the supporting material. When the transparent
supporting substrate 10 is used as the supporting material
as described above, the microlens (second concavity and
20 convexity layer) can be directly used for manufacturing
the light extraction transparent substrate for an organic
EL element without peeling the microlens from the
supporting material. Thus, the step of manufacturing an
organic EL element can be simplified. Particularly when
25 a substrate in which the diffraction grating 11 is formed
on the transparent supporting substrate 10 is used as the
109
NOPF12-509
supporting material, the substrate can be used directly
as the light extraction transparent substrate for an
organic EL element. In addition, a microlens is obtained
in a state of being stacked on a resin film (a film of TAC,
5 PET, COP, PC, or the like) used as the supporting material,
and the film in the stacked state may be stacked on the
transparent supporting substrate 10. In addition, the
thickness of the supporting material is not particularly
limited, and is preferably within a range from 1 to 500
10 urn.
Subsequently, in the microlens formation step, a
microlens comprising a second concavity and convexity layer
is obtained by detaching the master block for forming a
microlens form the cured layer. A method for detaching
15 the master block from the cured concavity and convexity
layer (a layer obtained by curing the microlens formation
material, for example, a cured resin layer or the like)
as described above is not particularly limited, and a known
method can be employed as appropriate. Thus, a microlens
20 comprising the second concavity and convexity layer having
the second concavities and convexities formed thereon can
be obtained on the supporting material. Note that, after
the microlens is formed as described above, the light
extraction transparent substrate for an organic EL element
25 may be manufactured by peeling the microlens from the
supporting material, and stacking the peeled microlens on
110
NOPF12-509
the transparent supporting substrate 10 with a
pressure-sensitive adhesive layer and/or an adhesive layer
interposed therebetween. Alternatively, when the
transparent supporting substrate 10 is used as the
5 supporting material, the microlens may be directly used
for manufacturing the light extraction transparent
substrate without peeling the microlens. Moreover, when
a transparent resin film or the like is used as the supporting
material, the film on which the microlens is stacked may
10 also be directly stacked on the transparent supporting
substrate 10 .
In addition, a method for manufacturing the light
extraction transparent substrate comprising the
transparent supporting substrate 10, the diffraction
15 grating 11, and the microlens 12 is not particularly limited,
and, for example, it is possible to employ a method in which
a separately manufactured microlens 12 is stacked on a
transparent supporting substrate 10 on which a diffraction
grating 11 is stacked, a method in which a microlens 12
20 is manufactured directly on another surface of a
transparent supporting substrate 10 on which a diffraction
grating 11 is stacked in advance, or a method in which a
diffraction grating 11 is manufactured directly on another
surface of a transparent supporting substrate 10 on which
25 a microlens 12 is stacked in advance.
When the light extraction transparent substrate 1
111
NOPF12-509
w
of the present invention as described above is used for
an organic EL element, a surface 10A of the transparent
supporting substrate 10 on which the diffraction grating
11 is formed is arranged on a surface (incident surface)
5 sideonwhichlightL from the organic EL element is incident,
and a surface 10B of the transparent supporting substrate
10 on which the microlens 12 is formed is arranged on a
surface (emitting surface) side on which the light L from
the organic EL element exits . By using the light extraction
10 transparent substrate 1 in this manner, light from the
organic EL can be extracted more efficiently.
In addition, since the diffraction grating 11 and
the microlens 12 are used in combination in the light
extraction transparent substrate 1, the light emission
15 efficiency can be improved sufficiently without increasing
the average height of the concavities and convexities of
the diffraction grating. Hence, life-shortening of the
organic EL element can be sufficiently suppressed, and also
the guided light can be sufficiently extracted. Moreover,
20 by the light extraction transparent substrate 1, the light
emission efficiency can be improved sufficiently, while
the angle-dependences of luminance and chromaticity are
sufficiently reduced.
Hereinabove, description is given of a preferred
25 embodiment of the light extraction transparent substrate
for an organic EL element of the present invention. However,
112
NOPF12-509
the light extraction transparent substrate for an organic
EL element of the present invention is not limited to the
embodiment. For example, in the embodiment shown in Fig.
1, the light extraction transparent substrate for an
5 organic EL element comprises the transparent supporting
substrate 10, the diffraction grating 11, and the microlens
12. However, unless effect s of the invent ion are impaired,
an adhesive layer, a pressure-sensitive adhesive layer,
a transparent resin layer (for example, a resin film usable
10 for an organic EL element (a film of TAC, PET, COP, PC,
or the like, etc.): note that the resin film used as the
supporting material in manufacturing the microlens, as it
is, may be used as the transparent resin layer), or the
like may be arranged between the transparent supporting
15 substrate 10 and the diffraction grating 11 or between the
transparent supporting substrate 10 and the microlens 12.
For example, a lamination structure such as a light
extraction transparent substrate 1 in an organic EL element
shown in Fig. 14 and described later may be employed.
20 (Organic EL Element)
Next, an organic EL element of the present invention
is described. Specifically, the organic EL element of the
present invention comprises:
a transparent supporting substrate;
25 a diffraction grating comprising a first concavity
and convexity layer which is disposed on one surface of
113
NOPF12-509
the transparent supporting substrate and which has first
concavities and convexities formed on a surface thereof;
a microlens comprising a second concavity and
convexity layer which is disposed on another surface of
5 the transparent supporting substrate and which has second
concavities and convexities formed on a surface thereof;
and
a transparent electrode , an organic layer, andametal
electrode, which are stacked in this order on the first
10 concavity and convexity layer, while being formed into such
shapes that a shape of the first concavities and convexities
formed on the surface of the first concavity and convexity
layer is maintained, wherein
a constituent unit formed by the transparent
15 supporting substrate, the diffraction grating, and the
microlens comprises the above-described light extraction
transparent substrate for an organic EL element of the
present invention.
Hereinafter, a preferred embodiment of the organic
20 EL element of the present invention will be described in
detail with reference to the drawings. Fig. 14 is a
cross-sectional view schematically showing the preferred
embodiment of the organic EL element of the present
invention. The organic EL element shown in Fig. 14
25 basically comprises: a light extraction transparent
substrate 1; a transparent electrode 51; an organic layer
114
NOPF12-509
52; a cathode buffer layer 53; and a metal electrode 54.
As the light extraction transparent substrate 1, the
above-described light extraction transparent substrate of
the present invention is used. Note that, in the light
5 extraction transparent substrate 1 used in this embodiment,
the microlens 12 is stacked on a surface of the transparent
supporting substrate 10 on an emitting surface side in an
organic EL element with an adhesive layer 13 and a
transparent resin layer 14 interposed therebetween, and
10 the diffraction grating 11 is stacked on another surface
thereof. The stacking structure between the microlens 12
and the transparent supporting substrate 10 can be easily
achieved as follows. Specifically, a transparent resin
film is used as a planate supporting substrate for
15 manufacturing the microlens 12, and an adhesive layer is
formed on another surface of the transparent resin film
in advance. Then, these are laminated on the transparent
supporting substrate 10.
In addition, the average height of the concavities
20 and convexities formed on the diffraction grating in the
light extraction transparent substrate 1 is preferably 20%
to 80% of the entire thickness of the organic layer 52 of
the organic EL element. If the average height of the
concavities and convexities is less than the lower limit
25 (less than 20%) , the average height of the concavities and
convexities is so insufficient that a sufficient
115
NOPF12-509
diffraction effect tends not to be obtained. Meanwhile,
if the average height exceeds the upper limit (if the average
height of the concavities and convexities is larger than
80% of the thickness of the organic layer), the
5 possibilities of occurrence of defects such as short
circuit between the anode and the cathode and insulation
breakdown of the light emitting layer; light emission
failure; life shortening; and the like tend to be high.
In addition, in the organic EL element shown in Fig.
10 14, the transparent elect rode 51, the organic layer 52 (hole
transporting layer 101/light emitting layer 102/hole
blocking layer 103/electron transporting layer 104), the
cathode buffer layer 53, and the metal electrode 54 are
stacked in this order on the surface of the light extraction
15 transparent substrate 1 on which the first concavities and
convexities of the diffraction grating (first concavity
and convexity layer) 11 are formed, while being formed into
such shapes that the shape of the first concavities and
convexities is maintained.
20 As a material for the transparent electrode 51, for
example, indium oxide, zinc oxide, tin oxide, indium-tin
oxide (ITO), which is a composite material thereof, gold,
platinum, silver, or copper is used. Of these materials,
ITO is preferable from the viewpoint of the balance between
25 the transparency and the electrical conductivity. In
addition, the thickness of the transparent electrode 51
116
NOPF12-509
is preferably within a range from 20 to 500 nm. If the
thickness is less than the lower limit, the electrical
conductivity tends to be insufficient. Meanwhile, if the
thickness exceeds the upper limit, the transparency tends
5 to be so insufficient that the emitted EL light cannot be
extracted to the outside sufficiently.
In the organic EL element shown in Fig. 14, the organic
layer 52 is a laminate comprising the hole transporting
layer 101, the light emitting layer 102, the hole blocking
10 layer 103, and the electron transporting layer 104. A
material for each of the hole transporting layer 101, the
light emitting layer 102, the hole blocking layer 103, and
the electron transporting layer 104 is not particularly
limited, and a known material can be used as appropriate.
15 Example of materials usable for the hole transporting layer
101 include derivatives of naphthyldiamine (a-NPD),
triphenylamine, triphenyldiamine derivatives (TPD),
benzidine, pyrazoline, styrylamine, hydrazone,
triphenylmethane, carbazole, and the like, etc. As a
20 material of the light emitting layer 102, for example, a
known material which emits light upon application of a
voltage can be used as appropriate. Here, examples of the
material which emits light upon application of a voltage
include a material obtained by doping
25 4,4'-N,N'-dicarbazole-biphenyl (CBP) with
tris(phenylpyridinato)iridium(III) complex (Ir(ppy)3);
117
NOPF12-509
materials made of fluorescent organic solids such as
8-hydroxyquinoline aluminum (Alq3, green, low molecular
weight), bis-(8-hydroxy)quinaldine aluminum phenoxide
(Alq'20Ph, blue, low molecular weight),
5 5, 10, 15, 20-tetraphenyl-21H,23H-porphine (TPP, red, low
molecular weight), poly(9,9-dioctylfluorene-2,7-diyl)
(PFO, blue, high molecular weight),
poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-(1-cyanovinyle
ne)phenylene] (MEH-CN-PPV, red, high molecular weight),
10 and anthracene; and the like. In addition, as the hole
blocking layer 103, a material (for example,
9-dimethyl-4,7-diphenyl-l,10-phenanthroline (BCP) or the
like) known as the so-called hole blocking material can
be used as appropriate. Moreover, aluminum quinolinol
15 complex, a phenanthroline derivative, an oxadiazole
derivative, a triazole derivative, a phenylquinoxaline
derivative, a silole derivative, or the like can be used
as a material of the electron transporting layer 104.
In addition, in the organic layer 52, the thicknesses
20 of the hole transporting layer 101, the light emitting layer
102, the hole blocking layer 103, and the electron
transporting layer 104 are preferably within a range from
5 to 200 nm (the hole transporting layer 101), within a
range from 5 to 200 nm (the light emitting layer 102) , within
25 a range from 1 to 50 nm (the hole blocking layer 103), and
within a range from 5 to 200 nm (the electron transporting
118
NOPF12-509
4&
layerl04), respectively, from the viewpoint of maintaining
the shape of the concavities and convexities formed on the
surface of the concavity and convexity layer. In addition,
the entire thickness of the organic layer 52 is preferably
5 within a range from 20 to 600 nm.
In addition, a metal fluoride such as lithium fluoride
(LiF) or Li203, a highly active alkaline earth metal such
as Ca, Ba, or Cs, or the like can be used as a material
of the cathode buffer layer 53. The thickness of the
10 cathode buffer layer 53 is preferably within a range from
0.5 to 10 nm.
Meanwhile, the metal electrode 54 is an electrode
made of a metal. A material of the metal electrode 54 is
not particularly limited, and a substance having a small
15 work function can be used as appropriate . Examples thereof
include aluminum, MgAg, Mgln, and AlLi. In addition, the
thickness of the metal electrode 54 is preferably within
a range from 50 to 500 nm. If the thickness is less than
the lower limit, the electrical conductivity tends to
20 decrease. Meanwhile, if the thickness exceeds the upper
limit, the concavity and convexity shape tends to be
difficult to maintain.
In the organic EL element of the present invention,
the transparent electrode 51, the organic layer 52, the
25 cathode buffer layer 53, and the metal electrode 54 are
each stacked on the surface of the first concavity and
119
NOPF12-509
convexity layer of the diffraction grating, while being
formed into such a shape that the shape of the first
concavities and convexities formed on the surface of the
first concavity and convexity layer of the diffraction
5 grating is maintained. Hence, stress generated when the
organic EL element is bent can be relaxed by the shape of
the concavities and convexities. For this reason, the
organic EL element of the present invention can be suitably
used as an organic EL element for flexible displays,
10 flexible lighting apparatuses, and the like, for which
flexibility is required.
In addition, in the organic EL element of the present
invention, part of constituent portions of the organic EL
element is constituted of the light extraction transparent
15 substrate 1 as described above. In such an organic EL
element, the diffraction grating 11 in the light extraction
transparent substrate 1 more preferably satisfy the
condition represented by the above-described inequality
(1) and/or the condition that the kurtosis (k) is -1.2 or
20 more (more preferably -1.2 to 1.2), from the viewpoint of
more sufficiently suppressing the generation of a leakage
current. Suppose that a light extraction transparent
substrate 1 comprising a diffraction grating (first
concavity and convexity layer) 11 satisfying such a
25 condition is used, and suppose that the shape of the first
concavities and convexities formed on the surface of the
120
NOPF12-509
diffraction grating (first concavity and convexity layer)
11 is maintained as it is in each of the transparent electrode
51, the organic layer 52, and the metal electrode 54 (note
that the cathode buffer layer 53 is not shown in Fig. 15)
5 as shown in Fig. 15 (suppose that each of the layers has
a uniform thickness in a direction perpendicular to the
surface of the transparent electrode substrate). In such
a case, regarding an inter-electrode distance between the
transparent electrode 51 and the metal electrode 54 in the
10 direction perpendicular to the surface of the transparent
electrode substrate (standard distance: the distance
represented by X in Fig. 15) and a distance at which an
inter-electrode distance between the transparent
electrode 51 and the metal electrode 54 is the shortest
15 (the shortest distance: the distance represented by Y in
Fig. 15) , which are determined on the basis of the concavity
and convexity analysis image of the first concavity and
convexity layer 11, the ratio of measuring points at which
the magnitude of the shortest distance Y is a half or less
20 of the standard distance X can be made 0 to 2% relative
to all the measuring points in the concavity and convexity
analysis. Note that the present inventors have found that
such regions where the magnitude of the shortest distance
Y is a half or less of the standard distance X are prone
25 to generation of a leakage current. The present inventors
have found, on the basis of this knowledge, that by making
121
NOPF12-509
the ratio of the regions where the magnitude of the shortest
distance Y is a half or less of the standard distance X
0 to 2%, the generation of a leakage current can be suppressed
sufficiently. Note that the ratio of the regions
5 (measuring points) where the magnitude of the shortest
distance Y is a half or less of the standard distance X
relative to all the regions (all the measuring points) is
herein referred to as "the ratio of the presence of
leakage-current prone regions."
10 As described above, in the organic EL element of the
present invention, the ratio of measuring points where the
magnitude of the shortest distance Y is a half or less of
the standard distance X (the ratio of the presence of
leakage-current prone regions) is preferably 0 to 2%
15 relative to all the measuring points in the concavity and
convexity analysis image, from the viewpoint of
sufficiently suppressing the leakage current. Here, the
ratio is determined from a distribution of the
inter-electrode distance, and this distribution of the
20 inter-electrode distance is determined on the basis of a
concavity and convexity analysis image obtained by
measuring the first concavity and convexity layer 11 by
employing the same method as the method for measuring the
median (M) and the average value (m) of the depth
25 distribution, on the assumption that the shape of the
concavities and convexities formed on the surface of the
122
NOPF12-509
first concavity and convexity layer 11 is maintained as
it is in each of the transparent electrode 51, the organic
layer 52, and the metal electrode 54. Specifically, in
the organic EL element of the present invention, the ratio
5 of the presence of leakage-current prone regions determined
from the distribution of the inter-electrode distance
between the transparent electrode 51 and the metal
electrode 54 is preferably 0 to 2%. Note that, in the
measurement of the distribution of the inter-electrode
10 distance, the standard distance X is preferably set
(assumed) to be within a range from 30 to 500 nm to meet
the actual design, and, for example, the standard distance
X is assumed to be 70 nm for an organic EL element in which
the thickness of the organic layer in the direction
15 perpendicular to the transparent supporting substrate is
70 nm. Then, the distribution of the shortest distance
is calculated on the basis of the concavity and convexity
analysis image (SPM image), and the ratio of the regions
(leakage-current prone regions) where the shortest
20 distance Y of the inter-electrode distance is a half or
less of the standard distance X relative to all the measuring
points in the measurement of the concavity and convexity
analysis image (SPM image) is calculated. Thus, the ratio
of the presence of the leakage-current prone regions can
25 be determined. Note that the calculation of the shortest
distance and the ratio of the presence of the
123
NOPF12-509
leakage-current prone regions can be determined by
calculation with a computer on the basis of analysis results
of the concavity and convexity analysis image of the
diffraction grating (first concavity and convexity layer)
5 11.
In addition, since each of the transparent electrode
51, the organic layer 52, the cathode buffer layer 53, and
the metal electrode 54 is stacked in the organic EL element
of the present invention, while being formed into such
10 shapes that the shape of the first concavities and
convexities formed on the surface of the diffraction
grating (first concavity and convexity layer) 11 is
maintained, it is possible to suppress the repetition of
multiple reflections of light generated at the organic
15 layer in the element due to total reflection at each
interface. In addition, it is also possible to re-emit
light, which has been reflected at an interface between
the transparent supporting substrate and the microlens 12,
by a diffraction effect. Moreover, since each of the
20 transparent electrode 51, the organic layer 52, and the
metal electrode 54 is stacked, while being formed into such
a shape that the shape of the first concavities and
convexities formed on the surface of the diffraction
grating (first concavity and convexity layer) 11 is
25 maintained, the inter-electrode distance between the
transparent electrode 51 and the metal electrode 54 is short
124
NOPF12-509
in some portions as described above. For this reason, in
comparison with those in which the inter-electrode distance
between the transparent electrode 51 and the metal
electrode 54 is uniform, an increase in electric field
5 intensity can be expected in application of a voltage, and
also the light emission efficiency of the organic EL element
can be improved. In addition, if a control is made so that
the leakage-current prone regions can be 0 to 2%, the leakage
current can also be sufficiently prevented, and the light
10 emission efficiency of the organic EL element can be further
improved. As described above, according to the organic
EL element of the present invention, it is possible to
achieve a sufficient external extraction efficiency.
In addition, in the organic EL element of the present
15 invention, the microlens 12 is disposed on one surface of
the transparent supporting substrate 10. In the microlens
12, the shape of the second concavities and convexities
(such a shape that when a Fourier-transformed image is
obtained by performing two-dimensional fast Fourier
20 trans form processing on a concavity and convexity analysis
image obtained by analyzing the shape by use of an atomic
force microscope, the Fourier-transformed image shows a
circular or annular pattern substantially centered at an
origin at which an absolute value of wavenumber is 0 urn-1)
25 is formed. Hence, the concavities and convexities have
a concavity and convexity shape isotropic in any
125
NOPF12-509
cross-sectional direction. For this reason, not only the
light extraction efficiency can be sufficiently high, but
also light can be sufficiently stably emitted in every angle.
Hence, the angle-dependence of the emitted light and the
5 change in chromaticity can be sufficiently reduced.
Note that a method for manufacturing the organic EL
element of the present invention is not particularly
limited, and, for example, the organic EL element may be
manufactured by employing a method for manufacturing an
10 organic EL element described below. Specifically, as the
method for manufacturing an organic EL element, a method
may be employed which comprises: a step of preparing the
above-described light extraction transparent substrate
for an organic EL element of the present invention; and
15 a step (organic EL element formation step) of stacking,
on a surface of the first concavity and convexity layer
(diffraction grating) of the light extraction transparent
substrate for an organic EL element, each of the transparent
electrode, the organic layer, and the metal electrode,
20 which are formed into such shapes that the shape of the
first concavities and convexities formed on the surface
of the first concavity and convexity layer is maintained,
thereby obtaining an organic EL element. Hereinafter,
each of the steps is described, with a case where an organic
25 EL element of the embodiment shown in Fig . 1 4 is manufactured
being taken as an example.
126
NOPF12-509
As the step of preparing the above-described light
extraction transparent substrate for an organic EL element
of the present invention, the method for manufacturing a
light extraction transparent substrate described above for
5 the light extraction transparent substrate for an organic
EL element of the present invention can be employed as
appropriate.
Subsequently, in the organic EL element formation
step, first, a transparent electrode 51 is stacked on a
10 diffraction grating (first concavity and convexity layer)
11 as shown in Fig. 14, while being formed into such a shape
that the shape of the first concavities and convexities
formed on the surface of the first concavity and convexity
layer 11 is maintained. As a material of the transparent
15 electrode 51, the same materials as those described as the
materials of the transparent electrode 3 in the organic
EL element of the present invention can be used. In
addition, as a method for stacking the transparent
electrode 51, a known method such as a vapor deposition
20 method or a sputtering method can be employed as appropriate
Of these methods, a vapor deposition method is preferably
employed from the viewpoint of maintaining the shape of
the first concavities and convexities formed on the surface
of the first concavity and convexity layer.
25 Inaddition, in the organic EL element format ion step ,
next, an organic layer 52 is stacked on the transparent
127
NOPF12-509
electrode 51 as shown in Fig. 14, while being formed into
such a shape that the shape of the first concavities and
convexities formed on the surface of the first concavity
and convexity layer 11 is maintained. As the kind and
5 material of the organic layer 52 , the same kind and material
as those described above for the organic layer of the organic
EL element of the present invention can be used. In
addition, the organic layer 52 may have a structure of the
laminate comprising the hole transporting layer 101/the
10 light emitting layer 102/the hole blocking layer 103/the
electron transporting layer 104 as shown in Fig. 14 (the
sign "/" indicates that the adjacent layers are stacked
on each other) , for example. In addition, as a method for
stacking the organic layer 52, a known method such as a
15 vapor deposition method or a sputtering method can be
employed as appropriate. Of these methods, a vapor
deposition method is preferably employed from the viewpoint
of maintaining the shape of the first concavities and
convexities formed on the surface of the first concavity
20 and convexity layer 11.
When the organic EL element shown in Fig. 14 is
manufactured, subsequently, a cathode buffer layer 53 and
a metal electrode 54 are stacked on the organic layer 52,
while being formed into such shapes that the shape of the
25 first concavities and convexities formed on the surface
of the first concavity and convexity layer 11 is maintained,
128
NOPF12-509
1^
in the organic EL element formation step. As materials
of the cathode buffer layer 53 and the metal electrode 54,
the same materials as those described above for the organic
EL element of the present invention can be used. In
5 addition, as a method for stacking each of the cathode buff er
layer 53 and the metal electrode 54, a known method such
as a vapor deposition method or a sputtering method can
be employed as appropriate. Of these methods, a vapor
deposition method is preferably employed from the viewpoint
10 of maintaining the shape of the first concavities and
convexities formed on the surface of the first concavity
and convexity layer 11.
In addition, the method for manufacturing the organic
EL element is not limited to the above-described method,
15 and the following method may be employed. Specifically,
a diffraction grating is formed on a transparent supporting
base member. Then, a laminate of a transparent supporting
base member 10, a diffraction grating 11, a transparent
electrode 51, an organic layer 52, a cathode buffer layer
20 53, and a metal electrode 54 is obtained by subjecting the
diffraction grating to the above-described organic EL
element formation step. After that, a separately
manufactured microlens 12 is laminated thereon. When such
a method is employed, the final yield of the manufacturing
25 of the organic EL element can also be improved for the
following reasons. Specifically, when a scar or a defect
129
NOPF12-509
is found in the microlens (second concavity and convexity
layer) 12, such a portion can be removed. Moreover, when
a defect is found on the element side, the defective part
can be removed.
5 The organic EL element obtained according to the
method for manufacturing an organic EL element of the
present invention as described above has a sufficiently
high light extraction efficiency, and is capable of
sufficiently stably emitting light in every angle and
10 sufficiently reducing the angle-dependence of the emitted
light and the change in chromaticity.
Hereinabove, the preferred embodiment of the organic
EL element of the present invention is described. However,
the organic EL element of the present invention is not
15 limited to the above-described embodiment. For example,
although the organic layer 52 of the embodiment shown in
Fig. 14 has the following structure (A):
(A) hole transporting layer 101/light emitting layer
102/hole blocking layer 103/electron transporting layer
20 104 (the sign "/" indicates that the adjacent layers are
stacked on each other) , the structure of the organic layer
52 is not particularly limited. A known structure of an
organic layer of an organic EL element can be employed as
appropriate. For example, the organic layer may have any
25 of the following structures (B) to (E) :
(B) light emitting layer/electron transporting layer,
130
NOPF12-509
(C) hole transporting layer/light emitting layer/electron
transporting layer,
(D) hole transporting layer/light emitting layer/hole
blocking layer/electron transporting layer, and
5 (E) hole transporting layer/electron transporting layer.
Moreover, the cathode buffer layer is stacked in the
structure of the embodiment shown in Fig. 14. However,
the organic EL element of the present invention only needs
to comprise the above-described light extraction
10 transparent substrate for an organic EL element of the
present invention, a transparent electrode, an organic
layer, and a metal electrode. The other constituents are
not particularly limited, and it is not necessary to stack
the cathode buffer layer. In addition, from the same
15 viewpoint, an anode buffer layer may be further stacked
between the transparent electrode 51 and the organic layer
in the organic EL element of the present invention. As
a material of the anode buffer layer, a known material can
be used as appropriate, and examples thereof include copper
20 phthalocyanine, PEDOT, and the like. In addition, the
thickness of the anode buffer layer is preferably 1 to 50
nm. Moreover, a manufacturing method for a case where the
anode buffer layer is used is not particularly limited,
and a known method capable of manufacturing an anode buffer
25 layer can be employed as appropriate.
[Examples]
131
NOPF12-509
Hereinafter, the present invention is described more
specifically on the basis of Example and Comparative
Examples. However, the present invention is not limited
to Example below.
5 First, a block copolymer 1 used in Example and
Comparative Example below is described. In the block
copolymer 1, polystyrene (hereinafter, abbreviated as "PS"
as appropriate) was used as a first polymer segment, and
polymethyl methacrylate (hereinafter, abbreviated as
10 " PMMA" as appropriate) was used as a second polymer segment.
The volume ratio of the first and second polymer segments
(first polymer segment: second polymer segment) in the block
copolymer was calculated on the assumption that the density
of polystyrene was 1 . 05 g/cm3, and the density of polymethyl
15 methacrylate was 1.19 g/cm3 . The number average molecular
weights (Mn) and weight average molecular weights (Mw) of
the polymer segments and the polymer were measured by gel
permeation chromatography (Model No: "GPC-8020"
manufactured by Tosoh Corporation, in which TSK-GEL
20 SuperHlOOO, SuperH2000, SuperH3000, and SuperH4000 were
connected in series). The glass transition temperatures
(Tg) of the polymer segments were measured by using a
differential scanning calorimeter (manufactured by
Perkin-Elmer under the product name of "DSC7"), while the
25 temperature was raised at a rate of temperature rise of
20°C/min over a temperature range from 0 to 200°C. The
132
NOPF12-509
solubility parameters of polystyrene and polymethyl
methacrylate are 9.0 and 9.3, respectively (see Kagaku
Binran Ouyou Hen ( Handbook of Chemist ry, Applied Chemist ry)
2nd edition).
5
A block copolymer of PS and PMMA (manufactured by
Polymer Source Inc),
Mn of PS segment=868,000,
Mn of PMMA segment=857,000,
10 Mn of block copolymer=l,725,000
Volume ratio of PS segment to PMMA segment
(PS:PMMA)=53:47,
Molecular weight distribution (Mw/Mn)=1.30,
Tg of PS segment=96°C,
15 Tg of PMMA segment=l10°C.

A method for measuring a concavity and convexity shape
is described. Specifically, first, for each of concavity
and convexity shapes formed in diffraction gratings and
20 microlenses of Example etc. , a randomly selected measuring
region of 3 um square (length: 3 urn, width: 3 urn) was analyzed
by use of an atomic force microscope (a scanning probe
microscope equipped with an environment control unit
"Nanonavi II Station/E-sweep" manufactured by SII
25 NanoTechnology Inc.) under the following analysis
conditions:
133
NOPF12-509
Measurement mode: dynamic force mode
Cantilever: SI-DF40 (material: Si, lever width: 40 um,
diameter of tip of chip: 10 nm)
Measurement atmosphere: in air
5 Measurement temperature: 25°C.
Thus, a concavity and convexity analysis image (SPM image)
of the concavity and convexity shape was obtained. Next,
a flattening process including primary inclination
correction was performed on the obtained concavity and
10 convexity analysis image, and then two-dimensional fast
Fourier transform processing was performed thereon to
obtain a Fourier-transformed image. Then, on the basis
of the concavity and convexity analysis image and the
Fourier-transformed image, the average height of the
15 concavities and convexities, the average pitch of the
concavities and convexities, and the pattern of the
Fourier-transformed image of each of the diffraction
gratings and micro lenses were determined. Note that, for
each diffraction grating, average values of the heights
20 and distances of concavities and convexities at 100 points
were employed as the average height of the concavities and
convexities and the average pitch of the concavities and
convexities, while, for each microlens, average values of
heights and distances of the concavities and convexities
25 at 10 points were employed as the average height of the
concavities and convexities and the average pitch of the
134
NOPF12-509
V
concavities and convexities.
In addition, the median (M) of the depth distribution
of the concavities and convexities, the average value (m)
of the depth distribution, and the kurtosis (k) of each
5 diffraction grating were also determined on the basis of
the concavity and convexity analysis image. Note that the
median (M) of the depth distribution of the concavities
and convexities, the average value (m) of the depth
distribution, and the kurtosis (k) were determined by
10 employing the same methods as the above-described methods
for measuring the median (M) of the depth distribution of
the concavities and convexities of the first concavity and
convexity layer, the average value (m) of the depth
distribution thereof, and for measuring the kurtosis.
15 (Example 1)

A block copolymer solution was obtained by dissolving
150 mg of the block copolymer 1 and 38 mg of polyethylene
20 glycol 4,000 (Mw=3000, Mw/Mn=1.10) manufactured by Tokyo
Chemical Industry Co., Ltd., as polyethylene oxide in
toluene, which was added thereto with the total amount being
10 g, followed by filtration through a membrane filter
having a pore diameter of 0.5 urn. Next, the thus obtained
25 block copolymer solution was applied by spin coating in
a filmthickness of 200 to 250 nm onto a polyphenylene sulfide
135
NOPF12-509
film (TORELINA manufactured by Toray Industries, Inc.)
serving as a base material. The spin coating was performed
at a spin speed of 500 rpm for 10 seconds, and subsequently
at 800 rpm for 30 seconds . Afterthat, the thin film applied
5 by the spin coating was dried by being left at room
temperature for 10 minutes.
Subsequently, the base material on which the thin
film was formed was heated in an oven of 170°C for 5 hours
(first heating step). Concavities and convexities were
10 observed on the surface of the thin film heated as described
above, indicating that micro phase separation of the block
copolymer constituting the thin film occurred. Note that
a cross-section of the thin film was observed with a
transmission electron microscope (TEM) (H-7100FA
15 manufactured by Hitachi, Ltd.) . The micro phase
separation was confirmed also by the image of the
cross-section.
Next, PMMA was removed by selective decomposition
from the block copolymer layer on the base material by
20 performing the following etching treatment on the thin film
subjected to the first heating step. In the
decomposition-removal step, first, the thin film was
irradiated with ultraviolet rays at an irradiation
intensity of 30 J/cm2 by use of a high pressure mercury
25 lamp. Subsequently, the thin film was immersed in acetic
acid to remove PMMA by selective decomposition, washed with
136
NOPF12-509
C
ion-exchanged water, and then dried. Note that a
measurement by a transmission electron microscope (TEM)
showed that, from the concavities and convexities generated
on the surface of the thin filmby the first heat treatment,
5 an apparently deep concavity and convexity pattern was
formed on the base material by the decomposition-removal
step.
Subsequently, the base material having the concavity
and convexity pattern formed by the etching treatment was
10 subjected to a heat treatment (second heating step) in an
oven of 140°C for 1 hour. A thin nickel layer of about
10 nm was formed as a current seed layer by sputtering on
a surface of the thin film subjected to the second heating
step and having the concavity and convexity pattern formed
15 thereon. Subsequently, the base material having the thin
film on which the nickel layer was formed was subjected
to an electroforming treatment (maximum current density:
0.05 A/cm2) in a sulfamic acid-nickel bath at a temperature
of 50°C, and nickel was deposited to a thickness of 250
20 urn. Thus, an electroplating layer (metal layer) was formed
on the nickel layer (seed layer) . The thus formed
nickel-elect rof ormed article (one in which the nickel layer
as the electroplating layer was stacked on the nickel layer
as the seed layer) was mechanically peeled from the base
25 material having the thin film on which the concavity and
convexity pattern was formed. Subsequently, the
137
NOPF12-509
nickel-electroformed article peeled from the base material
as described above was immersed in Chemisol 2303
manufactured by The Japan Cee-Bee Chemical Co., Ltd., and
washed with stirring at 50°C for 2 hours. After that, the
5 polymer component attached on the surface of the
electroformed article was removed by repeating application
of an acrylic UV curable resin onto the
nickel-electroformed article, curing of the acrylic UV
curable resin, and peeling of the acrylic UV curable resin
10 threetimes. Thus, a mold for forming a di f fraction grating
comprising the nickel-electroformed article having
concavities and convexities formed on the surface thereof
was obtained.
Observation of a cross-section of the thus obtained
15 mold for forming a diffraction grating with a scanning
electronmicroscope (FE-SEM: S4800 manufactured by Hitachi ,
Ltd.) showed that the concavities and convexities of the
nickel-electroformed article were smooth, and each convex
portion had a smooth mountain-like shape.
20 Subsequently, the mold for forming a diffraction
grating was immersed in HD-2101TH manufactured by Daikin
Chemicals Sales, Ltd. for approximately 1 minute, dried,
and then allowed to stand overnight. On the next day, the
mold for forming a diffraction grating was immersed in HDTH
25 manufactured by Daikin Chemicals Sales, Ltd., and washed
by being subjected to an ultrasonic wave treatment for
138
NOPF12-509
c
approximately 1 minute. Thus, a mold-release treatment
was performed on the surface of the mold for forming a
diffraction grating.

A fluorine-containing UV curable resin was applied
onto a glass substrate (12 mm in length, 20 mm in width,
and 0.7 mm in thickness) , and was cured by irradiation with
ultraviolet rays at 600 mJ/cm2, with the mold for forming
10 a diffraction grating subjected to the mold-release
treatment being pressed thereto. After the resin was cured
as described above, the mold for forming a diffraction
grating was peeled from the cured resin. Thus, the glass
substrate was obtained on which a diffraction grating was
15 stacked. Here, the diffraction grating comprised a cured
resin film to which the concavity and convexity shape on
the surface of the mold for forming a diffraction grating
was transferred.
Fig. 16 shows a Fourier-transformed image of the thus
20 obtained diffraction grating. As is apparent from the
Fourier-transformed image shown in Fig. 16, it was found
that the Fourier-transformed image showed a circular
pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 urn-1, and that the annular
25 pattern was such that 90% or more of all the bright spots
constituting the Fourier-transformed image were present
139
NOPF12-509
V
in a region where an absolute value of wavenumber was within
a range of 10 urn-1 or less. Moreover, the average height
of the concavities and convexities formed on the surface
of the diffraction grating was 54 nm, and the average pitch
5 thereof was 605 nm. In addition, the median (M) of the
depth distribution of the concavities and convexities was
50.892 nm, the average value (m) of the depth distribution
was 47.434 nm, and the kurtosis (k) was -0.973. Note that,
on the basis of the concavity and convexity analysis image
10 (SPM image), the ratio of the presence of the
above-described "leakage-current prone regions (regions
where the shortest distance of the inter-electrode distance
was a half or less of the standard distance X based on a
calculated distribution of the shortest distance" was
15 determined to be 0%.

First, a silicone-based polymer (a resin mixture
composition of 90% by mass of a silicone rubber
20 [manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601A"] and 10% by mass of a curing agent
[manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601B"] ) was appliedbya spin coating method
onto a polymer film formation substrate (material: glass,
25 thickness: 1.1 mm, size: 17x13 mm) to achieve a thickness
of 22.5 urn after the application, and then cured by heating
140
NOPF12-509
at 100°C for 1 hour. Thus, a first silicone-based polymer
film was formed.
Next, the base material on which the first
silicone-based polymer film was formed was placed in a
5 vacuum chamber, and a first aluminum vapor-deposition film
(thickness: 100 nm) was formed by a vapor deposition method
on the first silicone-based polymer film under conditions
of a temperature of 80°C and a pressure of 1*10~3 Pa. Thus,
a first laminate was obtained in which the first aluminum
10 vapor-deposition film was formed on the first
silicone-basedpolymer film. Then, the first laminate was
cooled in the vacuum chamber to room temperature (25°C)
in 1 hour. After that, the pressure inside the vacuum
chamber was returned to atmospheric pressure (1.013><105
15 Pa) . By cooling the first laminate as described above,
concavities and convexities were formed on the surface of
the first aluminum vapor-deposition film formed on the
first silicone-based polymer film.
Subsequently, a silicone-based polymer (a resin
20 mixture composition of 90% by mass of a silicone rubber
[manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601A"] and 10% by mass of a curing agent
[manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601B"]) was applied by a dropping method
25 onto the first aluminum vapor-deposition film to achieve
a thickness of 1.5 mm after the application, then cured
141
NOPF12-509
C
by heating in an oven at 60°C for 2 hours, and then detached
from the first aluminum vapor-deposition film. Thus, a
first mold was obtained.
Next, another base material (material: glass,
5 thickness: 1.1 mm, size: 17x13 mm) was prepared, and an
ultraviolet-ray-curable epoxy resin (manufactured by
Norland under the product name of "N0A81") was applied by
a dropping method onto the base material to achieve a
thickness of 100 urn after the application. Thus, a coating
10 film was formed. Then, the ultraviolet-ray-curable epoxy
resin was cured by irradiation with ultraviolet rays for
10 minutes, with the first mold being pressed to the surface
of the coating film. Subsequently, the first mold was
detached. Thus, a first epoxy resin film (second mold)
15 was obtained which had concavities and convexities formed
on the surface thereof and originated from the concavity
and convexity shape of the first mold.
Subsequently, a silicone-based polymer (a resin
mixture composition of 90% by mass of a silicone rubber
20 [manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601A"] and 10% by mass of a curing agent
[manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601B"]) was applied by a dropping method
onto the first epoxy resin film to achieve a thickness of
25 1.5 mm after the application, then cured by heating in an
oven at 60°C for 2 hours, and then detached from the first
142
NOPF12-509
V
epoxy resin film. Thus, a second silicone-based polymer
film (third mold) was obtained which had concavities and
convexities formed on the surface thereof and originated
from the concavity and convexity shape of the first epoxy
5 resinfilm (Notethat, asisapparent from the manufacturing
methods thereof, the concavity and convexity shape of the
first mold was inverted or transferred in each of the first
epoxy resin film and the second silicone-based polymer film
obtained as described above, and the first epoxy resin film
10 and the second silicone-based polymer film as they are can
be used also as master blocks for forming a microlens) .
Next, the second silicone-based polymer film was
placed in a vacuum chamber, and a second aluminum
vapor-deposition film (thickness: 100 nm) was formed by
15 a vapor deposition method under conditions of a temperature
of 80°C and a pressure of lxl0~3 Pa on the surface of the
second silicone-based polymer film on which the concavities
and convexities were formed. Thus, a second laminate was
obtained in which the second aluminum vapor-deposition film
20 was formed on the second silicone-based polymer film . Then,
the second laminate was cooled in the vacuum chamber to
room temperature (25°C) inlhour. Afterthat, thepressure
inside the vacuum chamber was returned to atmospheric
pressure (1.013><105 Pa) . By cooling the second laminate
25 as described above , concavities and convexities were formed
on the surface of the second aluminum vapor-deposition film
143
NOPF12-509
formed on the second silicone-based polymer film.
Next, another base material (material: glass,
thickness: 1.1 mm, size: 17x13 mm) was prepared, and an
ultraviolet-ray-curable epoxy resin (manufactured by
5 Norland under the product name of "N0A81") was applied by
a dropping method onto the base material to achieve a
thickness of 10 0 urn after the application . Thus, a coating
film was formed. Then, the ultraviolet-ray-curable epoxy
resin was cured by irradiation with ultraviolet rays for
10 10 minutes, with the second laminate being pressed to the
surface of the coating film. Subsequently, the second
laminate was detached. Thus, a second epoxy resin film
(fourth mold) was obtained which had concavities and
convexities formed on a surface thereof and originated from
15 the concavity and convexity shape of the second laminate.
Subsequently, a silicone-based polymer (a resin
mixture composition of 90% by mass of a silicone rubber
[manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601A"] and 10% by mass of a curing agent
20 [manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601B"]) was applied by a dropping method
onto the second epoxy resin film to achieve a thickness
of 1.5 mm after the application, then cured by heating in
an oven at 60°C for 2 hours, and then detached from the
25 second epoxy resin film. Thus, a third silicone-based
polymer film (fifth mold) was obtained which had
144
NOPF12-509
W
concavities and convexities formed thereon and originated
from the concavity and convexity shape of the second epoxy
resin film.
Next, the third silicone-based polymer film was
5 placed in a vacuum chamber, and a third aluminum
vapor-deposition film (thickness: 100 nm) was formed by
a vapor deposition method under conditions of a temperature
of 80°C and a pressure of 1*10~3 Pa on the surface of the
third silicone-based polymer film on which the concavities
10 and convexities were formed. Thus, a third laminate was
obtained in which the third aluminum vapor-deposition film
was formed on the third silicone-based polymer film. Then,
the third laminate was cooled in the vacuum chamber to room
temperature (25°C) in 1 hour. After that, the pressure
15 inside the vacuum chamber was returned to atmospheric
pressure (1.013*105 Pa) . By cooling the third laminate
as described above, concavities and convexities were formed
on the surface of the third aluminum vapor-deposition film
formed on the third silicone-based polymer film.
20 Subsequently, another base material (material: glass,
thickness: 1.1 mm, size: 17x13 mm) was prepared, and an
ultraviolet-ray-curable epoxy resin (manufactured by
Norland under the product name of "N0A81") was applied by
a dropping method onto the base material to achieve a
25 thickness of 100 um after the application . Thus, a coating
film was formed. Then, the ultraviolet-ray-curable epoxy
145
NOPF12-509
W
resin was cured by irradiation with ultraviolet rays for
10 minutes, with the third laminate being pressed to the
surface of the coating film. Subsequently, the third
laminate was detached. Thus, a third epoxy resin film
5 (sixth mold) was obtained which had concavities and
convexities formed on a surface thereof and originated from
the concavity and convexity shape of the third laminate.
Subsequently, a silicone-based polymer (a resin
mixture composition of 90% by mass of a silicone rubber
10 [manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601A"] and 10% by mass of a curing agent
[manufactured by Wacker Chemie AG under the product name
of "Elastosil RT601B"]) was applied by a dropping method
onto the third epoxy resin film to achieve a thickness of
15 1.5 mm after the application, then cured by heating in an
oven at 60°C for 2 hours, and then detached from the third
epoxy resin film. Thus, a master block (seventh mold) for
forming a microlens was obtained which was made of the
silicone-based polymer and which had concavities and
20 convexities formed thereon and originated from the
concavity and convexity shape of the third epoxy resin film.

As a supporting material, a resin substrate (TAC
film/adhesive layer/PET mold-release film) was prepared
25 in which an adhesive layer having a thickness of 25 nm and
being made of an acrylic adhesive agent and a mold-release
146
NOPF12-509
film made of PET were stacked on one surface of a triacetyl
cellulose film (TAC film, 12 mm in length, 20 mm in width)
having a thickness of 40 nm.
Then, an ultraviolet-ray-curable epoxy resin
5 (manufactured by Norland under the product name of "N0A8 1" )
was applied by a dropping method onto the surface of the
TAC film of the resin substrate (supporting material) to
achieve a thickness of 10 um after the application. Thus,
a coating film was formed. Then, the
10 ultraviolet-ray-curable epoxy resin was cured by
irradiation with ultraviolet rays for 10 minutes, with the
master block (seventh mold) for forming a microlens made
of the silicone-based polymer being pressed to the surface
of the coating film. Subsequently, the master block for
15 forming a microlens was detached. Thus, a resin substrate
was obtained on which a microlens made of the cured resin
film (thickness: 10 um) having a concavity and convexity
shape was stacked. Here, concavities and convexities
originated from the concavity and convexity shape of the
20 master block for forming a microlens were formed on the
surface of the cured resin film.
Fig. 17 shows a Fourier-transformed image of the
thus obtained microlens. As is apparent from the
Fourier-transformed image shown in Fig. 17, it was found
25 that the Fourier-transformed image showed a circular
pattern substantially centered at an origin at which an
147
NOPF12-509
absolute value of wavenumber was 0 urn"1, and the annular
pattern was such that 90% or more of all the bright spots
constituting the Fourier-transformed image were present
within a region where an absolute value of wavenumber was
5 1 jam"1 or less. In addition, the average height of the
concavities and convexities formed on the surface of the
microlens was 840 nm, and the average pitch thereof was
3.1 urn.

10 First, a laminate for an organic EL element was
obtained as follows by using the glass substrate obtained
as described above on which the diffraction grating was
stacked. Specifically, on the surface of the diffraction
grating on the glass substrate, a transparent electrode
15 (ITO, thickness: 120 nm), a hole transporting layer (a-NPD,
thickness: 30 nm) , a light emitting layer, (a layer of CBP
doped with 7.0 mo 1% of Ir(ppy)3 complex, thickness: 30 nm),
a hole blocking layer (10-phenanthroline (BCP), thickness:
5 nm) , an electron transporting layer (aluminum quinolinol
20 complex (Alq3), thickness: 50 nm) , a cathode buffer layer
(lithium fluoride (LiF), thickness: 1.5 nm) , and a metal
electrode (aluminum, thickness: 50 nm) were each stacked
by a vapor deposition method, while being formed into such
a shape that the shape of the concavities and convexities
25 formed on the surface of the diffraction grating (first
concavity and convexity layer: cured resin layer) was
148
NOPF12-509
C
maintained. Note that, in the laminate, glass
substrate/diffraction grating/transparent
electrode/hole transporting layer/light emitting
layer/hole blocking layer/electron transporting
5 layer/cathode buffer layer/metal electrode were stacked
in this order.
Next, the PET mold-release film was peeled from the
resin substrate (TAC film/adhesive layer/PET mold-release
film) obtained as described above on which the microlens
10 was stacked. The adhesive layer appearing on the surface
was laminated on the surface of the glass substrate of the
laminate for an organic EL element, and the adhesive layer
was cured. Thus, an organic EL element was obtained which
had a structure as shown in Fig. 14 (microlens (10 urn)/TAC
15 film (40 nm)/adhesive layer (25 nm)/glass substrate (0.7
mm)/diffraction grating (5 urn)/transparent electrode (120
nm)/hole transporting layer (30 nm)/light emitting layer
(30 nm)/hole blocking layer (5 nm)/electron transporting
layer ( 50 nm)/cathode buff er layer (1. 5 nm) /metal electrode
20 (50 nm) ) .
(Comparative Example 1)
An organic EL element for comparison (microlens/TAC
film/adhesive layer/glass substrate/transparent
electrode/hole transporting layer/light emitting
25 layer/hole blocking layer/electron transporting
layer/cathode buffer layer/metal electrode) was obtained
149
t)
NOPF12-509
by employing the same method as that of Example 1, except
that a glass substrate (12 mm in length, 20 mm in width,
and 0.7 mm in thickness) was used instead of the glass
substrate on which the diffraction grating was stacked.
5 (Comparative Example 2)
An organic EL element for comparison (hemispherical
lens/epoxy resin adhesive layer (dropping method)/glass
substrate/diffract ion grating/transparent
electrode/hole transporting layer/light emitting
10 layer/hole blocking layer/electron transporting
layer/cathode buffer layer/metal electrode) was obtained
by employing the same method as that of Example 1, except
for the following point. Specifically, the laminate of
the microlens, the TAC film, and the adhesive layer was
15 not stacked on the surface of the glass substrate by using
the resin substrate on which the microlens was stacked,
but a hemispherical lens having a diameter of 5 mm
(manufactured by Edmund) was stacked on the surface of the
glass substrate by using an uncured
20 ultraviolet-ray-curable epoxy resin (manufactured by
Norland under the product name of "NOA81") as an adhesive
agent.
(Comparative Example 3)
An organic EL element for comparison (hemispherical
25 lens/epoxy resin adhesive layer/glass
substrate/transparent electrode/hole transporting
150
NOPF12-509
layer/light emitting layer/hole blocking layer/electron
transporting layer/cathode buffer layer/metal electrode)
was obtained by employing the same method as that of Example
1, except for the following points. Specifically, a glass
5 substrate (12 mm in length, 20 mm in width, and 0.7 mm in
thickness) was used instead of the glass substrate on which
the diffraction grating was stacked. In addition, the
laminate of the microlens, the TAC film, and the adhesive
layer was not stacked on the surface of the glass substrate
10 by using the resin substrate on which the microlens was
stacked, but a hemispherical lens having a diameter of 5
mm (manufactured by Edmund) was stacked on the surface of
the glass substrate by using an uncured
ultraviolet-ray-curable epoxy resin (manufactured by
15 Norland under the product name of "NOA81") as an adhesive
agent.
(Comparative Example 4)
An organic EL element for comparison (glass
substrate/diffraction grating/transparent
20 electrode/hole transporting layer/light emitting
layer/hole blocking layer/electron transporting
layer/cathode buffer layer/metal electrode) was obtained
by employing the same method as that of Example 1, except
that the step of stacking the laminate of the microlens,
25 the TAC film, and the adhesive layer on the surface of the
glass substrate by use of the resin substrate on which the
151
c
NOPF12-509
microlens was stacked was not carried out.
(Comparative Example 5)
An organic EL element for comparison (glass
substrate/transparent electrode/hole transporting
5 layer/light emitting layer/hole blocking layer/electron
transporting layer/cathode buffer layer/metal electrode)
was obtained by employing the same method as that of Example
1, except that a glass substrate (12 mm in length, 20 mm
in width, and 0.7 mm in thickness) was used instead of the
10 glass substrate on which the diffraction grating was
stacked, and that the step of stacking the laminate of the
microlens, the TAC film, and the adhesive layer on the
surface of the glass substrate by use of the resin substrate
on which the microlens was stacked was not carried out.
15 [Performance Evaluations of Organic EL Elements Obtained
in Example 1 and Comparative Examples 1 to 5]
(i) Measurement of Light Emission Efficiency
The light emission efficiencies of the organic EL
elements obtained in Example 1 and Comparative Examples
20 1 to 5 were measured by the following method . Specifically,
a voltage was applied to an organic EL element, and then
the applied voltage (V) and a current (I) flowing through
the organic EL element were measured with a measuring
instrument (manufactured by ADVANTEST CORPORATION, model
25 No: R6244), and a luminance (L) was measured with a
spectrometer (Solid LambdaCCD UV-NIR manufactured by
152
NOPF12-509
Spectra Co-op) . On the basis of the thus obtained measured
values of the applied voltage (V), the current (I), and
the light emission luminance (L) , a current efficiency was
calculated by using the following calculation formula ( Fl) ,
5 and a power efficiency was calculated by using the following
calculation formula (F2):
(Current efficiency)=(L/I)•••(Fl),
(Power efficiency)=(L/I/V)•••(F2).
Then, values (ratios of the current efficiency and the
10 voltage efficiency with respect to those of Comparative
Example 5) normalized to reference values (takenasl) which
were the values of the organic EL element obtained in
Comparative Example 5 in which neither a microlens nor a
diffraction grating was used. Table 1 shows the obtained
15 results .
(ii) Measurement of Capability of Preventing Leakage
Current
On the basis of the values of the applied voltage
(V) , the current (I) , and the light emission luminance (L)
20 measured in (i) Measurement of Light Emission Efficiency
described above, the presence or absence of generation of
a leakage current was evaluated by making a comparison as
to the relationship between the current and the luminance
at the same voltage. Table 1 shows the obtained results.
25 (iii) Measurement of Angle-Dependence of Luminance
By using each of the organic EL elements obtained
153
NOPF12-509
P
in Example 1 and Comparative Examples 1 to 5, an intensity
of an emission spectrum was measured from an integral area
of an emission spectrum of light having wavelengths of 450
to 7 0 0 nm at each of 33 measurement positions whose measuring
5 angles ranged from -80° to 80° with intervals of 5 degrees,
where a direction perpendicular to the glass substrate was
defined as a measuring angle of 0°. For the measurement
of the intensity of the emission spectrum, a measuring
apparatus manufactured by Ocean Optics under the product
10 name of "USB-2000" was used, and a spectrum of light emitted
from a randomly selected measuring point on the organic
EL element upon application of a voltage of approximately
10 V to the organic EL element was measured. In addition,
for the measurement of the intensity of the emission
15 spectrum, the distance between a light-receiving portion
for receiving the emission spectrum and the measuring point
on the surface of the organic EL element was set to 10 cm.
Then, the measured value of the intensity of the
emission spectrum at each measuring angle determined as
20 described above was normalized to the value of an intensity
of an emission spectrum measured at a measuring angle of
0°. Thus, a normalized value of the intensity of the
emission spectrum (a value obtained by dividing the value
measured at each measuring angle by the value measured at
25 a measuring angle of 0°) was found. Then, a calculation
was performed according to the inequality:
154
NOPF12-509
Z = S(y(G)-yo(e) ) 2
[in the formula, 9 represents the above-described 33
measuring angles, y(9) represents the normalized values
of the intensities of the emission spectra at the angles
5 9, andy0(9) represent s theoretical values , determined from
a radiation pattern based on the Lambert law, of intensities
of emission spectra at the angles 9] . On the basis of the
obtained value of Z, the angle-dependence of luminance was
evaluated. Note that a smaller value of Z (the sum of
10 squares of the differences between the normalized values
and the theoretical values) indicates that the radiation
pattern is closer to the radiation pattern of the Lambert
law, and the value of Z can be used as an index of the
angle-dependence of luminance. Table 1 shows the obtained
15 results.
(iv) Measurement of Color Coordinate
By employing the same measuring method as the method
for measuring an intensity of an emission spectrum employed
in (iii) Measurement of Angle-Dependence of Luminance
20 described above, intensities of emission spectra of light
having wavelengths of 380 to 780 nm were measured for the
organic EL elements obtained in Example 1 and Comparative
Examples 1 to 5. On the basis of the data on the intensities
of the emission spectra, a u'v' chromaticity diagram (CIE
25 1976 UCS chromaticity diagram) was obtained. Then,
distances (Ac) between the coordinate point in the u'v'
155
NOPF12-509
chromaticity diagram for a case where the measuring angle
G was 0° and the coordinate point in the u'v' chromaticity
diagram for each measuring angle 9 in the measurement of
the intensities of the emission spectra were found, and
5 the maximum value thereof was found (the range of the numeric
values of Ac was found). Note that a smaller change in
the value of Ac indicates more reduced change in
chromaticity. Table 1 shows the obtained results.
[Table 1]
156
>
w
H-
0)
DJ
&)
CD
rti-
i
O
3
r t
0)
0)
w
c
Example 1
Comp. Ex. 1
Comp. Ex. 2
Comp. Ex. 3
Comp. Ex. 4
Comp. Ex. 5
Structure of element
Diffraction grating
Concavity and
convexity resin film
None
Concavity and
convexity resin film
None
Concavity and
convexity resin film
None
Microlens
Concavity and
convexity resin film
Concavity and
convexity resin film
Hemispherical lens
Hemispherical lens
None
None
Overall
thickness
(Mm)
1500
1500
5400
5400
1400
1400
Current
efficiency
1.61
1.21
2.48
1.68
1.45
1.00
Voltage
efficiency
1.99
1.17
3.34
1.85
1.74
1.00
Angledependence
of luminance
(z value)
0.013
0.016
0.878
0.780
0.028
0.026
Angle-dependence
of chromaticity
(Condition of Ac)
Ac<0.006
Ac<0.003
Ac<0.025
Ac<0.025
Ac<0.012
Ac<0.012
Presence or
absence of
leakage current
Absent
Absent
Absent
Absent
Absent
Absent
w
o
s
3
i-3
tr
NOPF12-509
it was found that the organic EL element (Example 1) of
the present invention comprising the light extraction
transparent substrate for an organic EL element of the
present invention had sufficiently higher current and
5 voltage efficiencies, a higher light emission efficiency,
and a sufficiently higher level of extraction efficiency
of light to the outside than the organic EL element obtained
in Comparative Example 5 in which the glass substrate was
used as the light-extraction surface, and neither a
10 diffract ion grating nor a microlens was used . Inaddition,
it was found that although the organic EL elements obtained
in Comparative Examples 2 and 3 in which the hemispherical
lens was used as a microlens had very high values of the
current efficiency and the voltage efficiency, the
15 angle-dependence of luminance and the angle-dependence of
chromaticity were large, and hence it can be said that these
organic EL elements were not necessarily sufficient in a
practical sense. On the other hand, it can be understood
that the organic EL element (Example 1) of the present
20 invention showed a radiation pattern close to that based
on the Lambert law, because the angle-dependence of
luminance was low, and it was found that the
angle-dependence of light emission was sufficiently
reduced in the organic EL element of the present invention.
25 Moreover, the thickness of the element structure of the
organic EL element (Example 1) of the present invention
158
NOPF12-509
c
can be sufficiently smaller than those of the organic EL
elements obtained in Comparative Examples 2 and 3. Also
from such a viewpoint, it can be said that the organic EL
element (Example 1) of the present invention is highly
5 practical. Furthermore, as is apparent from the fact that
the value of Ac was less than 0.006 at any measuring angle,
it was found that the angle-dependence of chromaticity of
the organic EL element (Example 1) of the present invention
was remarkably reduced, and the change in chromaticity
10 thereof was remarkably reduced. In addition, it can be
understood that the organic EL element for comparison
(Comparative Example 1) in which no diffraction grating
was used, but only a microlens comprising a cured resin
film having concavities and convexities formed thereon was
15 highly practical, because the improvement in light emission
efficiency, reduction of the angle-dependence of luminance,
and the reduction of the angle-dependence of chromaticity
were achieved in a well-balanced manner. However, it can
be understood that the organic EL element for comparison
20 (Comparative Example 1) was not necessarily sufficient in
terms of light emission efficiency, when compared with the
organic EL element (Example 1) of the present invention.
In addition, the organic EL element for comparison
(Comparative Example 4) in which no microlens was used,
25 but only the diffraction grating was used achieved the
improvement in light emission efficiency, the reduction
159
NOPF12-509
of the angle-dependence of luminance, and the reduction
of the angle-dependence of chromaticity in a well-balanced
manner. However, it can be understood that the organic
EL element for comparison (Comparative Example 4) was not
5 necessarily sufficient in terms of the reduction of the
angle-dependence of luminance and the reduction of the
angle-dependence of chromaticity, when compared with the
organic EL element (Example 1) of the present invention.
From these results, it was found that the improvement in
10 light emission efficiency, the reduction of the
angle-dependence of luminance, and the reduction of the
angle-dependence of chromaticity were exhibited at
extremely high levels in a well-balanced manner when the
light extraction transparent substrate for an organic EL
15 element (Example 1) of the present invention was used which
comprised: the diffraction grating being located on one
surface of the transparent supporting substrate and having
the first concavities and convexities formed thereon; and
the microlens being located on another surface and having
20 the second concavities and convexities formed thereon,
wherein the shape of the first concavities and convexities
and the shape of the second concavities and convexities
were each such that when a Fourier-transformed image was
obtained by performing two-dimensional fast Fourier
25 trans form processing on a concavity and convexity analysis
image obtained by analyzing the shape of the concavities
160
NOPF12-509
and convexities by use of an atomic force microscope, the
Fourier-transformed image showed a circular or annular
pattern substantially centered at an origin at which an
absolute value of wavenumber is 0 urn-1.
5 (Reference Example 1)

First, a mold comprising a nickel-electroformed
article whose surface was subjected to a mold-release
10 treatment (hereinafter, simply referred to as mold (A))
was obtained by employing the same method as the method
for preparing a master block (mold) for forming a
diffraction grating employed in Example 1. Next, a mold
(B) for forming a diffraction grating was manufactured by
15 using the thus obtained mold (A) . Specifically, a
fluorine-containing UV curable resin (manufactured by
Asahi Glass Co., Ltd. under the product name of "NIF") was
applied onto a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.), and the mold (A)
20 comprising the nickel-electroformed article was pressed
thereto. Then, the fluorine-containing UV curable resin
was cured by irradiation with ultraviolet rays at 60 0 mJ/cm2,
and then the mold (A) was peeled off. Thus, the mold (B)
for forming a diffraction grating which was made of the
25 UV curable resin film to which the surface shape of the
mold (A) was transferred was obtained. The thickness of
161
NOPF12-509
the UV curable resin to which the surface shape was
transferred was 1 urn.

First, 2.5 g of tetraethoxysilane (TEOS) and 2.1 g
5 of methyltriethoxysilane (MTES) were added dropwise to a
liquid obtained by mixing 24 . 3 g of ethanol, 2 . 16 g of water,
and 0.0094 g of concentrated hydrochloric acid, and the
mixture was stirred at 23°C and at a humidity of 45% for
2 hours. Thus, a sol was obtained. Subsequently, the sol
10 was applied onto a glass substrate having a thickness of
0.7 mm (made from soda lime) with a bar coater. Thus, a
coating film of the sol was formed on the glass substrate.
Then, 60 seconds after the formation of the coating film,
the mold (B) manufactured in Example 1 was pressed to the
15 coating film on the glass substrate by using a heated
pressing roll, and by employing a method shown below . Thus,
a diffraction grating (a concavity and convexity layer)
was formed on the glass substrate.
Specifically, first, the pressing roll used had a
20 heater therein and an outer periphery covered with a
heat-resistant silicone having a thickness of 4 mm. The
roll diameter was 50 mm, and the length of the roll in the
axial direction was 350 mm. Then, the surface of the mold
(B) on which the concavity and convexity pattern was formed
25 was pressed to the coating film on the glass substrate,
while the pressing roll heated at 80°C was rotated from
162
NOPF12-509
one end to the other end of the glass substrate. After
completion of the pressing of the mold (B) as described
above, the mold (B) was peeled from the one end to the other
end at a peeling angle of approximately 30° by hand. Then,
5 after the mold (B) was peeled, a glass substrate provided
with a cured coating film having concavities and
convexities formed thereon and originated from the
concavities and convexities of the mold (B) was heated at
300°C for 60 minutes by using an oven. Thus, the glass
10 substrate on which a diffraction grating (concavity and
convexity layer) made of an inorganic layer was stacked
was obtained. Note that the thickness of the inorganic
layer was 0.3 urn.
It was found that a Fourier-transformed image of the
15 thus obtained diffract ion grating ( inorganic layer ) showed
a circular pattern substantially centered at an origin at
which an absolute value of wavenumber was 0 urn""1, and the
circular pattern was such that 90% or more of all the bright
spots constituting the Fourier-transformed image were
20 present within a region where an absolute value of
wavenumber waswithinarangeof lOym^or less. Inaddition,
the average height of the concavities and convexities
formed on the surface of the diffraction grating was 71.5
nm, and the average pitch thereof was 375 nm. In addition,
25 the median (M) of the depth distribution of the concavities
and convexities was 49.6 nm, the average value (m) of the
163
NOPF12-509
depth distribution thereof was 50.3 nm, the standard
deviation (o) of the distribution of the depths of the
concavities and convexities was 19.3 nm, and the kurtosis
(k) was -0.15.
[Industrial Applicability]
As described above, the present invention makes it
possible to provide a light extraction transparent
substrate for an organic EL element, the light extraction
transparent substrate being capable of sufficiently
improving the light extraction efficiency of an organic
EL element, sufficiently reducing the change in
chromaticity, and sufficiently reducing the
angle-dependence of luminance . The present invention also
makes it possible to provide an organic EL element using
the same.
Hence, the light extraction transparent substrate
for an organic EL element of the present invention is
extremely useful as a transparent substrate for an organic
EL element used for white illumination and the like, etc.
[Reference Signs List]
1: light extraction transparent substrate
10: transparent supporting substrate
10A: incident surface of transparent supporting substrate
of light of organic EL element
10B: emitting surface of transparent supporting substrate
of light of organic EL element
164
NOPF12-509
11: diffraction grating (first concavity and convexity
layer)
11': diffraction grating formation material
12: microlens (second concavity and convexity layer)
13: adhesive layer
14: transparent resin layer
21: concavity and convexity layer made of first polymer
segment
22: seed layer
23: metal layer (electroplating layer)
30: transfer master member
31: master block (mold) for forming diffraction grating
40: substrate for forming polymer film
41: polymer film
42: vapor-deposition film
43: master block (mold) for forming microlens
43': master block material
51: transparent electrode
52: organic layer
53: cathode buffer layer
54: metal electrode
101: hole transporting layer
102: light emitting layer
103: hole blocking layer
104: electron transporting layer
L: arrow conceptually indicating direction in which light
165
NOPF12-509
of organic EL element travels
0: light-receiving portion of emission spectrum measuring
apparatus
S: surface of second concavity and convexity layer
P: randomly selected measuring point on surface of second
concavity and convexity layer
LI: line segment connecting point P and point 0
A: arrow conceptually indicating direction perpendicular
to surface of second concavity and convexity layer
X: inter-electrode distance (standard distance) between
transparent electrode and metal electrode
Y: distance (the shortest distance) which is the shortest
inter-electrode distance between the transparent
electrode and the metal electrode
166

NOPF12-509
[CLAIMS]
[Claim 1]
A light extraction transparent substrate for an
organic EL element, which is used by being disposed on an
5 emitting surface side of light in the organic EL element,
the light extraction transparent substrate comprising:
a transparent supporting substrate;
a diffraction grating which comprises a first
concavity and convexity layer having first concavities and
10 convexities formed on a surface thereof and which is located
on a surface of the transparent supporting substrate, the
surface serving as an incident surface of the light of the
organic EL element when the transparent supporting
substrate is used in the organic EL element; and
15 a microlens which comprises a second concavity and
convexity layer having second concavities and convexities
formed on a surface thereof and which is located on a surface
of the transparent supporting substrate, the surface
serving as an emitting surface of the light of the organic
20 EL element when the transparent supporting substrate is
used in the organic EL element, wherein
a shape of the first concavities and convexities and
a shape of the second concavities and convexities are each
such that when a Fourier-transformed image is obtained by
25 performing two-dimensional fast Fourier transform
processing on a concavity and convexity analysis image
167
NOPF12-509
4%
obtained by analyzing the shape of the concavities and
convexities by use of an atomic force microscope, the
Fourier-transformed image shows a circular or annular
pattern substantially centered at an origin at which an
5 absolute value of wavenumber is 0 urn-1.
[Claim 2]
The light extraction transparent substrate for an
organic EL element according to claim 1, wherein
the circular or annular pattern of the
10 Fourier-transformed image of the shape of the first
concavities and convexities is present within a region
where an absolute value of wavenumber is within a range
of 10 urn-1 or less, and
the circular or annular pattern of the
15 Fourier-transformed image of the shape of the second
concavities and convexities is present within a region
where an absolute value of wavenumber is within a range
of 1 urn"1 or less.
[Claim 3]
20 The light extraction transparent substrate for an
organic EL element according to claim 1 or 2, wherein
the first concavities and convexities have an average
height of 30 to 100 nm and an average pitch of 10 to 700
nm, and
25 the second concavities and convexities have an
average height of 400 to 1000 nm and an average pitch of
168
NOPF12-509
J?"
2 t o 10 urn.
[ C l a im 4]
iolN^-
0 6 NOV 2013
The light extraction transparent substrate for an
organic EL element according to any one of claims 1 to 3,
5 wherein
an average value and a median of a depth distribution
of the first concavities and convexities satisfy a
condition represented by the following inequality (1):
0.95xY